Definition
Beta-Casomorphins are peptides resulting from the digestion of beta-Casein and vary from 4-11 amino acids in length1. They exhibit opioid or morphine-like functions1.
Discovery
ß-Casomorphins were first purified from casein digest of guinea pig ileum based on their ability to show opioid activity2.
Classification
ß-Casomorphins are opioid peptides1. Several naturally occurring ß-Casomorphins (BCM) have been identified: Bovine BCM-4, Bovine BCM-5, Bovine BCM-6, Bovine BCM-7, Bovine BCM-8, Bovine BCM-11, Human BCM-7, Human BCM-81. Several analogues which are structurally modified variants of naturally occurring BCMs have been synthesized1.
Structural Characteristics
BCMs are 4-11 amino acids in length. The sequences of naturally occurring BCMs are given below1:
Bovine BCM-4 Tyr-Pro-Phe-Pro,
Bovine BCM-5 Tyr-Pro-Phe-Pro-Gly
Bovine BCM-6 Tyr-Pro-Phe-Pro-Gly-Pro
Bovine BCM-7 Tyr-Pro-Phe-Pro-Gly-Pro-Ile
Bovine BCM-8 Tyr-Pro-Phe-Pro-Gly-Pro-Ile-Pro
Bovine BCM-11 Tyr-Pro-Phe-Pro-Gly-Pro-Ile-Pro-Asn-Ser-Leu
Human BCM-7 Tyr-Pro-Phe-Val-Glu-Pro-Ile
Human BCM-8 Tyr-Pro-Phe-Val-Glu-Pro-Ile-Pro
Some sequences of BCM analoges are shown below3:
H-Tyr-Pro-Phe-Pro-Gly-EtDA-Gly-II
H-Tyr-Pro-Phe-Pro-Gly-EtDA-Gly-Gly-II
H-Tyr-Pro-Phe-Pro-Gly-EtDA-Gly-Gly-CO-CH3
H-Tyr-Pro-Phe-Pro-Gly-EtDA-Gly-Gly-CO-CH2-CH2-COOH
Mode of action
Not much has been studies on the exact mechanism of BCM function. It is known that they exert their opioid functions by binding to opioid receptors on cell membranes4. Recent studies have shown that BCM-7 is a high affinity ligand for angiotensin receptor in the brain4.
Functions
BCMs produce effects in the gastrointestinal tract. For instance they influence post prandial metabolism by stimulating the secretion of insulin and somatostatin and modulate transfer of amino acids in the intestine5. The affect hypoxia as it has been shown that BCM7 when administered to pregnant rats induces their recovery from hypoxic condition4. BCM-5 and analogs are involved in producing rotational behavior in rats6. BCM-8 is involved in interplay between mother and child during lactation7. Finally, BCMs have been implicated in several diseases including SIDS and childhood autism1.
References
1. Kamiñski S, Cieoeliñska A, Kostyra E (2007). Polymorphism of bovine beta-casein and its potential effect on human health. J Appl Genet, 48(3), 189–198.
2. Ramabadran K, Bansinath M (1989). Pharmacology of beta-casomorphins, opioid peptides derived from milk protein. Asia Pac J Pharmacol, 4, 45–58.
3. Sobirov MM, Khalikov ShKh, Saidov SS, Kodirov MZ, Zaitsev SV, Chichenkov ON, Varfolomeev SD (1994). Synthesis and biological activity of new analogs of beta-casomorphine-5. Bioorg Khim., 20(7), 740-50.
4. Book: Handbook of Biologically Active Peptides by Abba J. Kastin.
5. Zoghbi S, Trompette A, Claustre J, Homsi ME, Garzo´n J, Jourdan G, Scoazec JY and Plaisancie P (2006). Casomorphin-7 regulates the secretion and expression of gastrointestinal mucins through a opioid pathway. Am J Physiol Gastrointest Liver Physiol 290, G1105–G1113.
6. Marschitz HM, Terenius L, Grehn L, Ungerstedt U (1989). Rotational behaviour produced by intranigral injections of bovine and human beta-casomorphins in rats. Psychopharmacology (Berl), 99(3), 357-61.
7. Ivano DN, Richard JF, Hannu JTK, Yves LR, Chris TL, Inga T, Daniel T, Renger W, (2009). Review of the potential health impact of ß-casomorphins and related peptides. EFSA Scientific Report, 231, 1-107.
Saturday, June 27, 2009
α-Casein Exorphins
Definition
a-Casein exorphins are peptides isolated from a-Casein1. They have morphine-like opioid (narcotic) activity and hence are termed exorphins1.
Discovery
a-Casein exorphins were first purified from pepsin treated hydrolysates of a-Casein1. Their opiod activity was then determined by biochemical assays1.
Classification
a-Casein exorphins belong to the class of opioid peptides that also includes exorphins that are proteins absorbed by the digested food and endorphins that are produced by the body itself1.
Structural Characteristic
They correspond to the sequences 90-96, Arg-Tyr-Leu-Gly-Tyr-Leu-Glu, and 90-95, Arg-Tyr-Leu-Gly-Tyr-Leu, of alpha-casein2. Two analogues of a-Casein exorphins, Tyr-Leu-Gly-Tyr-Leu-Glu (91-96) and Tyr-Leu-Gly-Tyr-Leu (91-95), have now been synthesized and characterized. They are all resistant to the action of trypsin2.
Mode of action
Not much is known about the mode of action of a-Casein exorphins. One study has indicated that these peptides may be efficient ligands for copper ions3.
Functions
a-Casein exorphins may have gastrointestinal and even neuronal functions1
References
1. Zioudrou C, Streaty RA, Klee WA (1979). Opioid peptides derived from food proteins. The exorphins. J Biol Chem., 254(7), 2446-9.
2. Loukas S, Varoucha D, Zioudrou C, Streaty RA, Klee WA (1983). Opioid activities and structures of alpha-casein-derived exorphins. Biochemistry, 22(19), 4567-73.
3. Lodyga-Chruscinska E, Micera G, Szajdzinska-Piêtek E, Sanna D (1998). Copper(II) Complexes of Opiate-like Food Peptides. J Agric Food Chem., 46(1), 115-118.
a-Casein exorphins are peptides isolated from a-Casein1. They have morphine-like opioid (narcotic) activity and hence are termed exorphins1.
Discovery
a-Casein exorphins were first purified from pepsin treated hydrolysates of a-Casein1. Their opiod activity was then determined by biochemical assays1.
Classification
a-Casein exorphins belong to the class of opioid peptides that also includes exorphins that are proteins absorbed by the digested food and endorphins that are produced by the body itself1.
Structural Characteristic
They correspond to the sequences 90-96, Arg-Tyr-Leu-Gly-Tyr-Leu-Glu, and 90-95, Arg-Tyr-Leu-Gly-Tyr-Leu, of alpha-casein2. Two analogues of a-Casein exorphins, Tyr-Leu-Gly-Tyr-Leu-Glu (91-96) and Tyr-Leu-Gly-Tyr-Leu (91-95), have now been synthesized and characterized. They are all resistant to the action of trypsin2.
Mode of action
Not much is known about the mode of action of a-Casein exorphins. One study has indicated that these peptides may be efficient ligands for copper ions3.
Functions
a-Casein exorphins may have gastrointestinal and even neuronal functions1
References
1. Zioudrou C, Streaty RA, Klee WA (1979). Opioid peptides derived from food proteins. The exorphins. J Biol Chem., 254(7), 2446-9.
2. Loukas S, Varoucha D, Zioudrou C, Streaty RA, Klee WA (1983). Opioid activities and structures of alpha-casein-derived exorphins. Biochemistry, 22(19), 4567-73.
3. Lodyga-Chruscinska E, Micera G, Szajdzinska-Piêtek E, Sanna D (1998). Copper(II) Complexes of Opiate-like Food Peptides. J Agric Food Chem., 46(1), 115-118.
Casein Kinase Substrates
Definition
Casein kinases are Ser/Thr protein kinases that have been implicated in cell cycle control, circadian rhythm, DNA repair and other cellular processes1. Several substrates of casein kianses have been identified and even synthesized artificially2.
Discovery
Casein kinase activity associated with the endoplasmic reticulum of mammary glands was first characterized in 19743.
Classification
Casein kinase belongs to the kinase family of proteins and its substrates that are proteins involved in various cellular processes are numerous in number. Two casein kinases have been widely studied: Casein kinase I and II3.
Structural Characteristics
The substrate for casein kinase I has the sequence motif –S(P)XXS-. The phosphorylated serine is known to be an effective substrate for the kinase4. Similarly the synthetic peptide, Arg-Arg-Arg-Glu-Glu-Glu-Thr-Glu-Glu-Glu serves as an effective substrate for casein kinase II5. In cells, substrates of casein kinase II have been found to have Leu-zipper motifs6.
Mode of action
Casein kinase I substrates bind to the active site of the kinase monomer where they are phosphorylated7. Casein kinase II normally binds to the leucine-zipper DNA binding domain of proteins6.
Functions
Casein kinase I substrates are involved in RNA metabolism (helicases and ribosomal proteins), glycogen metabolism (glycogen synthase), tumor suppression (p53), transcription (CREM), DNA repair and cell morphogenesis2. Casein kinase II substrates are mainly transcription factors (cMyc, cJun, cMyb), cofactors (PC4), basal factors (TFIIIB), viral transactivators (adenovirus E1A) and glycogen metabolism (glycogen synthase)6.
References
1. Burnett G and Kennedy E (1954). The enzymatic phosphorylation of proteins. J Biol. Chem., 211, 969-80.
2. Gao ZH., Metherall J., Virshup DM (2000). Identification of casein kinase I substrates by in vitro expression cloning screening. Biochem. and Biophy. Res. Comm., 268 (2), 562-66.
3. Bingham E and Farrel H (1974). Casein kinase from the Golgi apparatus of lactating mammary gland. J Biol.Chem., 249, 3647-51.
4. Flotow H and Roach P (1991). Role of Acidic Residues as Substrate Determinants for Casein Kinase I. J Biol. Chem., 266(6), 3724-27.
5. Kuenzel EA and Krebs EG (1995). A synthetic peptide substrate specific for casein kinase II (protein kinase/protein kinase specificity/peptide phosphorylation). Proc. Natl. Acad. Sci., 82, 737-41.
6. Yamaguchi Y, Wada T, Suzuki F, Takagi T, Hasegawa J, and Handa H (1998). Casein kinase II interacts with the bZIP domains of several transcription factors. Nucleic Acids Res, 26(16), 3854–3861.
7. Xu RM, Carmel G, Sweet RM, Kuret J, and Cheng X (1995). Crystal structure of caseinkinase-1, a phosphate-directed protein kinase. EMBO J, 14(5), 1015–1023.
Casein kinases are Ser/Thr protein kinases that have been implicated in cell cycle control, circadian rhythm, DNA repair and other cellular processes1. Several substrates of casein kianses have been identified and even synthesized artificially2.
Discovery
Casein kinase activity associated with the endoplasmic reticulum of mammary glands was first characterized in 19743.
Classification
Casein kinase belongs to the kinase family of proteins and its substrates that are proteins involved in various cellular processes are numerous in number. Two casein kinases have been widely studied: Casein kinase I and II3.
Structural Characteristics
The substrate for casein kinase I has the sequence motif –S(P)XXS-. The phosphorylated serine is known to be an effective substrate for the kinase4. Similarly the synthetic peptide, Arg-Arg-Arg-Glu-Glu-Glu-Thr-Glu-Glu-Glu serves as an effective substrate for casein kinase II5. In cells, substrates of casein kinase II have been found to have Leu-zipper motifs6.
Mode of action
Casein kinase I substrates bind to the active site of the kinase monomer where they are phosphorylated7. Casein kinase II normally binds to the leucine-zipper DNA binding domain of proteins6.
Functions
Casein kinase I substrates are involved in RNA metabolism (helicases and ribosomal proteins), glycogen metabolism (glycogen synthase), tumor suppression (p53), transcription (CREM), DNA repair and cell morphogenesis2. Casein kinase II substrates are mainly transcription factors (cMyc, cJun, cMyb), cofactors (PC4), basal factors (TFIIIB), viral transactivators (adenovirus E1A) and glycogen metabolism (glycogen synthase)6.
References
1. Burnett G and Kennedy E (1954). The enzymatic phosphorylation of proteins. J Biol. Chem., 211, 969-80.
2. Gao ZH., Metherall J., Virshup DM (2000). Identification of casein kinase I substrates by in vitro expression cloning screening. Biochem. and Biophy. Res. Comm., 268 (2), 562-66.
3. Bingham E and Farrel H (1974). Casein kinase from the Golgi apparatus of lactating mammary gland. J Biol.Chem., 249, 3647-51.
4. Flotow H and Roach P (1991). Role of Acidic Residues as Substrate Determinants for Casein Kinase I. J Biol. Chem., 266(6), 3724-27.
5. Kuenzel EA and Krebs EG (1995). A synthetic peptide substrate specific for casein kinase II (protein kinase/protein kinase specificity/peptide phosphorylation). Proc. Natl. Acad. Sci., 82, 737-41.
6. Yamaguchi Y, Wada T, Suzuki F, Takagi T, Hasegawa J, and Handa H (1998). Casein kinase II interacts with the bZIP domains of several transcription factors. Nucleic Acids Res, 26(16), 3854–3861.
7. Xu RM, Carmel G, Sweet RM, Kuret J, and Cheng X (1995). Crystal structure of caseinkinase-1, a phosphate-directed protein kinase. EMBO J, 14(5), 1015–1023.
CART (Cocaine- and Amphetamine-Regulated Transcript) Peptides
Definition
Cocaine- and amphetamine- regulated transcript (CART) peptides, derived from proCART polypeptide in humans are neuropeptides expressed in the brain1. They mainly serve as inhibitors of food intake1.
Discovery
CART was first purified by gel filtration and sequenced in 1980 from rat hypothalamus2.
Classification
CART is a neuropeptide family member2.
Structural Characteristics
CART gene encodes a peptide of either 129 or 116 amino acid residues in rat whereas only the short form exists in humans. The predicted signal sequence is 27 amino acid residues resulting in a precursor of 102 or 89 residues3. The C-terminal end of CART, consisting of 48 amino acid residues and 3 disulphide bonds, is thought to constitute a biologically active part of the molecule. Various CART peptides can be generated from the precursor: CARTs (55-102), (85-102), (55-76) and (62-76)3. CART (55-102) contains three disulphide bridges that are required for its function4.
Mode of action
The mode of action of CART peptides has not been fully established. Several studies have observed that they may function through CART receptors in turn activating down stream signaling pathways5.
Functions
CART is distributed in the central nervous system and periphery and has many physiological roles. It elicits similar behavior as cocaine. CART has been shown to have variety of effects on dopamine6. It increases blood pressure, has variety of behavioral effects and influences nociception6. In the hypothalamus CART mainly regulates energy homeostasis6. CART is also an endogenous inhibitor of food intake6. CART peptides are also important in anxiety, pain, arousal, startle response, regulation of calcium channels, and neuroendocrine hormone secretion5.
References
1. Thim L, Kristensen P, Larsen PJ, Wulff BS (1998). CART, a new anorectic peptide. Int J Biochem Cell Biol, 30(12), 1281-4.
2. Spiess J and Vale W (1980). Multiple forms of somatostatin-like activity in rat hypothalamus. Biochemistry 19, 2861–66.
3. Dylag T, Kotlinska J, Rafalski P, Pachuta A, Silberring J (2006). The activity of CART peptide fragments. Peptides, 27(8), 1926-33.
4. Murphy KG (2005). Dissecting the role of cocaine and amphetamine-regulated transcript (CART) in the control of appetite. Briefing in Functional Genomics and proteomic, 4 (2), 95–111.
5. Rogge G, Jones D, Hubert GW, Lin Y & Kuhar MJ (2008). CART peptides: regulators of body weight, reward and other functions. Nature Reviews Neuroscience, 9, 747-758.
6. Vicentic A, Jones DC (2007). The CART (cocaine- and amphetamine-regulated transcript) system in appetite and drug addiction. J Pharmacol Exp Ther., 320(2), 499-506.
Cocaine- and amphetamine- regulated transcript (CART) peptides, derived from proCART polypeptide in humans are neuropeptides expressed in the brain1. They mainly serve as inhibitors of food intake1.
Discovery
CART was first purified by gel filtration and sequenced in 1980 from rat hypothalamus2.
Classification
CART is a neuropeptide family member2.
Structural Characteristics
CART gene encodes a peptide of either 129 or 116 amino acid residues in rat whereas only the short form exists in humans. The predicted signal sequence is 27 amino acid residues resulting in a precursor of 102 or 89 residues3. The C-terminal end of CART, consisting of 48 amino acid residues and 3 disulphide bonds, is thought to constitute a biologically active part of the molecule. Various CART peptides can be generated from the precursor: CARTs (55-102), (85-102), (55-76) and (62-76)3. CART (55-102) contains three disulphide bridges that are required for its function4.
Mode of action
The mode of action of CART peptides has not been fully established. Several studies have observed that they may function through CART receptors in turn activating down stream signaling pathways5.
Functions
CART is distributed in the central nervous system and periphery and has many physiological roles. It elicits similar behavior as cocaine. CART has been shown to have variety of effects on dopamine6. It increases blood pressure, has variety of behavioral effects and influences nociception6. In the hypothalamus CART mainly regulates energy homeostasis6. CART is also an endogenous inhibitor of food intake6. CART peptides are also important in anxiety, pain, arousal, startle response, regulation of calcium channels, and neuroendocrine hormone secretion5.
References
1. Thim L, Kristensen P, Larsen PJ, Wulff BS (1998). CART, a new anorectic peptide. Int J Biochem Cell Biol, 30(12), 1281-4.
2. Spiess J and Vale W (1980). Multiple forms of somatostatin-like activity in rat hypothalamus. Biochemistry 19, 2861–66.
3. Dylag T, Kotlinska J, Rafalski P, Pachuta A, Silberring J (2006). The activity of CART peptide fragments. Peptides, 27(8), 1926-33.
4. Murphy KG (2005). Dissecting the role of cocaine and amphetamine-regulated transcript (CART) in the control of appetite. Briefing in Functional Genomics and proteomic, 4 (2), 95–111.
5. Rogge G, Jones D, Hubert GW, Lin Y & Kuhar MJ (2008). CART peptides: regulators of body weight, reward and other functions. Nature Reviews Neuroscience, 9, 747-758.
6. Vicentic A, Jones DC (2007). The CART (cocaine- and amphetamine-regulated transcript) system in appetite and drug addiction. J Pharmacol Exp Ther., 320(2), 499-506.
CaMK II (Ca2+/calmodulin-dependent protein kinase II)
Definition
Ca2+/calmodulin-dependent protein kinase II (CaMKII) is a Ser/Thr protein kinase whose activity is regulated by Ca2+/calmodulin (CaM) complex1. It is predominant in the heart and plays an important role during excitation contraction coupling2.
Discovery
CaMKII was first purified from rat brain by gel filtration techniques while monitoring the activation of tryptophan hydrolase and phosphorylation of endogenous proteins3.
Classification
CaMK proteins belong to the kinase family4. CaMKII belongs to the CaMK subfamily of proteins which include the following members: CaMKI, CaMKII-alpha subunit, CaMKII-beta subunit, CaMKII-gamma subunit, CaMKII-delta subunit, CaMKIII and CaMKIV4.
Structural Characteristics
The four isoforms of CaMKII (a,b,g,d) are all encoded by different genes. a and b are predominant neural isoforms while g and d isoforms are expressed in many tissues including the heart. The CaMKII consists of an N-terminal catalytic domain followed by autoinhibitory, Ca2+/CaM binding and association domains5. Predicted CaMKII phosphorylation consensus motifs generally follow the form R-X-X-S/T. The autoinhibitory domain consists of a pseudosubstrate sequence that, under basal conditions, binds and constrains the catalytic domain5. The pseudosubstrate sequence is built around an activating "autophosphorylation" site at Thr286/287 (the precise numbering is isoform dependent). The enzyme assembles into dodecameric or tetradecomeric structures, with the catalytic domains sticking out, such that these may phosphorylate residues in an intersubunit fashion that increases their affinity to CaM complex5. In the absence of Ca2+/calmodulin, the autoinhibitory domain inhibits the catalytic domain6.
Mode of action
When intracellular Ca2+ increases, CaM binds up to four Ca2+ ions to form the Ca2+/CaM complex that binds to the regulatory domain of CaMKII thereby activating the enzyme with half maximal activation at Ca2+. After this Ca2+/CaM-dependent activation, CaMKII autophosphorylates Thr286/287 on the autoinhibitory segment resulting in a completely active enzyme that can maintain CaMK active even after Ca2+ has declined5. Activated CaMKII can phosphorylate various substrates5.
Functions
CaMKII modulates excitation-contraction coupling in the heart by regulating several Ca2+ handling proteins5. CaMKII has also been implicated in Ca2+ dependent axonal growth cone attraction, synaptic plasticity, learning and memory7. Excess CaMKII is associated with heart failure. Hence CaMK inhibitors are being designed in order to study their effect on reducing heart failure5.
References
1. Maier LS (2009). Role of CaMKII for signaling and regulation in the heart. Front Biosci., 14:486-96.
2. Wayman GA, Lee YS, Tokumitsu H, Silva A, Soderling TR (2008). Calmodulin-kinases: modulators of neuronal development and plasticity. Neuron, 59(6), 914-31.
3. Yamauchi, T. and Fujisawa, H. (1980). Evidence for three distinct forms of calmodulin-dependent protein kinases from rat brain. FEBS Lett. 116, 141-144.
4. Steven KH and Tony H (1995). The eukaryotic protein kinase superfamily: kinase (catalytic) domam structure and classification. The Faseb Journal, 29, 576-96.
5. Couchonnal LF, Anderson ME (2008). The role of calmodulin kinase II in myocardial physiology and disease. Physiology (Bethesda).23:151-9.
6. Rosenberg OS, Deindl S, Sung RJ, Nairn AC, Kuriyan J (2005). Structure of the autoinhibited kinase domain of CaMKII and SAXS analysis of the holoenzyme. Cell, 123, 849–860.
7. Lars SM and Donald MB (2007). Role of Ca2+/calmodulin-dependent protein kinase (CaMK) in excitation–contraction coupling in the heart. Cardiovascular Research, 73(4), 631-640.
Ca2+/calmodulin-dependent protein kinase II (CaMKII) is a Ser/Thr protein kinase whose activity is regulated by Ca2+/calmodulin (CaM) complex1. It is predominant in the heart and plays an important role during excitation contraction coupling2.
Discovery
CaMKII was first purified from rat brain by gel filtration techniques while monitoring the activation of tryptophan hydrolase and phosphorylation of endogenous proteins3.
Classification
CaMK proteins belong to the kinase family4. CaMKII belongs to the CaMK subfamily of proteins which include the following members: CaMKI, CaMKII-alpha subunit, CaMKII-beta subunit, CaMKII-gamma subunit, CaMKII-delta subunit, CaMKIII and CaMKIV4.
Structural Characteristics
The four isoforms of CaMKII (a,b,g,d) are all encoded by different genes. a and b are predominant neural isoforms while g and d isoforms are expressed in many tissues including the heart. The CaMKII consists of an N-terminal catalytic domain followed by autoinhibitory, Ca2+/CaM binding and association domains5. Predicted CaMKII phosphorylation consensus motifs generally follow the form R-X-X-S/T. The autoinhibitory domain consists of a pseudosubstrate sequence that, under basal conditions, binds and constrains the catalytic domain5. The pseudosubstrate sequence is built around an activating "autophosphorylation" site at Thr286/287 (the precise numbering is isoform dependent). The enzyme assembles into dodecameric or tetradecomeric structures, with the catalytic domains sticking out, such that these may phosphorylate residues in an intersubunit fashion that increases their affinity to CaM complex5. In the absence of Ca2+/calmodulin, the autoinhibitory domain inhibits the catalytic domain6.
Mode of action
When intracellular Ca2+ increases, CaM binds up to four Ca2+ ions to form the Ca2+/CaM complex that binds to the regulatory domain of CaMKII thereby activating the enzyme with half maximal activation at Ca2+. After this Ca2+/CaM-dependent activation, CaMKII autophosphorylates Thr286/287 on the autoinhibitory segment resulting in a completely active enzyme that can maintain CaMK active even after Ca2+ has declined5. Activated CaMKII can phosphorylate various substrates5.
Functions
CaMKII modulates excitation-contraction coupling in the heart by regulating several Ca2+ handling proteins5. CaMKII has also been implicated in Ca2+ dependent axonal growth cone attraction, synaptic plasticity, learning and memory7. Excess CaMKII is associated with heart failure. Hence CaMK inhibitors are being designed in order to study their effect on reducing heart failure5.
References
1. Maier LS (2009). Role of CaMKII for signaling and regulation in the heart. Front Biosci., 14:486-96.
2. Wayman GA, Lee YS, Tokumitsu H, Silva A, Soderling TR (2008). Calmodulin-kinases: modulators of neuronal development and plasticity. Neuron, 59(6), 914-31.
3. Yamauchi, T. and Fujisawa, H. (1980). Evidence for three distinct forms of calmodulin-dependent protein kinases from rat brain. FEBS Lett. 116, 141-144.
4. Steven KH and Tony H (1995). The eukaryotic protein kinase superfamily: kinase (catalytic) domam structure and classification. The Faseb Journal, 29, 576-96.
5. Couchonnal LF, Anderson ME (2008). The role of calmodulin kinase II in myocardial physiology and disease. Physiology (Bethesda).23:151-9.
6. Rosenberg OS, Deindl S, Sung RJ, Nairn AC, Kuriyan J (2005). Structure of the autoinhibited kinase domain of CaMKII and SAXS analysis of the holoenzyme. Cell, 123, 849–860.
7. Lars SM and Donald MB (2007). Role of Ca2+/calmodulin-dependent protein kinase (CaMK) in excitation–contraction coupling in the heart. Cardiovascular Research, 73(4), 631-640.
CaMK (Ca2+/calmodulin-dependent protein kinase)
Definition
Ca2+/calmodulin-dependent protein kinase (CaMK) are a family of Ser/Thr protein kinases whose activity is regulated by Ca2+/calmodulin (CaM) complex and on activation, phosphorylate their protein substrates to alter their functionality1. They are primarily located in the brain and play a critical role in neuronal development, plasticity and behavior1.
Discovery
In 1979, the idea that CaMK exists arose from the observation that most of the Ca2+-dependent endogenous phosphorylation of rat brain cytosol proteins require calmodulin2. Later, in 1980, CaMKII was purified from rat brain by gel filtration techniques while monitoring the activation of tryptophan hydrolase and phosphorylation of endogenous proteins3.
Classification
CaMK proteins belong to the kinase family4. CaMK subfamily of proteins includes the following members: CaMKI, CaMKII-alpha subunit, CaMKII-beta subunit, CaMKII-gamma subunit, CaMKII-delta subunit, CaMKIII and CaMKIV4.
Structural Characteristics
The CaM kinases consist of an N-terminal catalytic domain followed by autoinhibitory and Ca2+/CaM binding domains. In addition CaMKII proteins have an association domain5. The enzymes assemble into dodecameric holoenzyme structures, with the catalytic domains sticking out, such that these may phosphorylate residues in an intersubunit fashion that increases their affinity to CaM complex6. In the absence of Ca2+/calmodulin, the autoinhibitory domain inhibits the catalytic domain6. Several CaM kinases aggregate into a homooligomer or heterooligomer. Phosphorylation at residues 286/305/306, which are all threonines, have a negative effect on binding of Ca2+/calmodulin complex to enzyme subunits, thus reducing function6.
Mode of action
When intracellular Ca2+ increases, CaM binds up to four Ca2+ ions to form the Ca2+/CaM complex that binds to the regulatory domain of CaMK thereby activating the enzyme with half maximal activation at Ca2+. After this Ca2+/CaM-dependent activation, CaMK autophosphorylates Thr287 on the autoinhibitory segment resulting in a completely active enzyme that can maintain CaMK active even after Ca2+ has declined7. Activated CaMKs can phosphorylate various substrates7.
Functions
CaMK proteins play an important role in the development of neurons8. CaMKK/CaMKI is involved in regulation of axonal growth cone morphology/motility and axonal outgrowth, dendritic arborization, and formation of dendritic spines8. CaMKII modulates excitation contraction coupling in the heart by regulating several Ca2+ handling proteins8. CaMKII has also been implicated in Ca2+ dependent axonal growth cone attraction, synaptic plasticity, learning and memory1. CaMKIV promotes dendritic growth by the activationof ErK1.
References
1. Wayman GA, Lee YS, Tokumitsu H, Silva A, Soderling TR (2008). Calmodulin-kinases: modulators of neuronal development and plasticity. Neuron, 59(6), 914-31.
2. Yamauchi T and Fujisawa H (1980). Evidence for three distinct forms of calmodulin-dependent protein kinases from rat brain. FEBS Lett., 116, 141-144.
3. Yamauchi T, Fujisawa H (1979). Most of the Ca2+-dependent endogenous phosphorylation of rat brain cytosol proteins requires Ca2+-dependent regulation protein. Biochem Biophys Res Commun., 90(4), 1172-8.
4. Steven KH and Tony H (1995). The eukaryotic protein kinase superfamily: kinase (catalytic) domam structure and classification. The Faseb Journal, 29, 576-96.
5. Thomas RS and James TS (2001). Structure and Regulation of Calcium/Calmodulin-Dependent Protein Kinase. Chem. Rev., 101 (8), 2341–52.
6. Rosenberg OS, Deindl S, Sung RJ, Nairn AC, Kuriyan J (2005). Structure of the autoinhibited kinase domain of CaMKII and SAXS analysis of the holoenzyme. Cell, 123, 849–860.
7. Lars SM and Donald MB (2007). Role of Ca2+/calmodulin-dependent protein kinase (CaMK) in excitation–contraction coupling in the heart. Cardiovascular Research, 73(4), 631-640.
8. Alicia M, Leticia V and Cecilia MW (2007). Ca2+/calmodulin-dependent protein kinase: A key component in the contractile recovery from acidosis. Cardiovascular Research, 73(4), 648-656.
Ca2+/calmodulin-dependent protein kinase (CaMK) are a family of Ser/Thr protein kinases whose activity is regulated by Ca2+/calmodulin (CaM) complex and on activation, phosphorylate their protein substrates to alter their functionality1. They are primarily located in the brain and play a critical role in neuronal development, plasticity and behavior1.
Discovery
In 1979, the idea that CaMK exists arose from the observation that most of the Ca2+-dependent endogenous phosphorylation of rat brain cytosol proteins require calmodulin2. Later, in 1980, CaMKII was purified from rat brain by gel filtration techniques while monitoring the activation of tryptophan hydrolase and phosphorylation of endogenous proteins3.
Classification
CaMK proteins belong to the kinase family4. CaMK subfamily of proteins includes the following members: CaMKI, CaMKII-alpha subunit, CaMKII-beta subunit, CaMKII-gamma subunit, CaMKII-delta subunit, CaMKIII and CaMKIV4.
Structural Characteristics
The CaM kinases consist of an N-terminal catalytic domain followed by autoinhibitory and Ca2+/CaM binding domains. In addition CaMKII proteins have an association domain5. The enzymes assemble into dodecameric holoenzyme structures, with the catalytic domains sticking out, such that these may phosphorylate residues in an intersubunit fashion that increases their affinity to CaM complex6. In the absence of Ca2+/calmodulin, the autoinhibitory domain inhibits the catalytic domain6. Several CaM kinases aggregate into a homooligomer or heterooligomer. Phosphorylation at residues 286/305/306, which are all threonines, have a negative effect on binding of Ca2+/calmodulin complex to enzyme subunits, thus reducing function6.
Mode of action
When intracellular Ca2+ increases, CaM binds up to four Ca2+ ions to form the Ca2+/CaM complex that binds to the regulatory domain of CaMK thereby activating the enzyme with half maximal activation at Ca2+. After this Ca2+/CaM-dependent activation, CaMK autophosphorylates Thr287 on the autoinhibitory segment resulting in a completely active enzyme that can maintain CaMK active even after Ca2+ has declined7. Activated CaMKs can phosphorylate various substrates7.
Functions
CaMK proteins play an important role in the development of neurons8. CaMKK/CaMKI is involved in regulation of axonal growth cone morphology/motility and axonal outgrowth, dendritic arborization, and formation of dendritic spines8. CaMKII modulates excitation contraction coupling in the heart by regulating several Ca2+ handling proteins8. CaMKII has also been implicated in Ca2+ dependent axonal growth cone attraction, synaptic plasticity, learning and memory1. CaMKIV promotes dendritic growth by the activationof ErK1.
References
1. Wayman GA, Lee YS, Tokumitsu H, Silva A, Soderling TR (2008). Calmodulin-kinases: modulators of neuronal development and plasticity. Neuron, 59(6), 914-31.
2. Yamauchi T and Fujisawa H (1980). Evidence for three distinct forms of calmodulin-dependent protein kinases from rat brain. FEBS Lett., 116, 141-144.
3. Yamauchi T, Fujisawa H (1979). Most of the Ca2+-dependent endogenous phosphorylation of rat brain cytosol proteins requires Ca2+-dependent regulation protein. Biochem Biophys Res Commun., 90(4), 1172-8.
4. Steven KH and Tony H (1995). The eukaryotic protein kinase superfamily: kinase (catalytic) domam structure and classification. The Faseb Journal, 29, 576-96.
5. Thomas RS and James TS (2001). Structure and Regulation of Calcium/Calmodulin-Dependent Protein Kinase. Chem. Rev., 101 (8), 2341–52.
6. Rosenberg OS, Deindl S, Sung RJ, Nairn AC, Kuriyan J (2005). Structure of the autoinhibited kinase domain of CaMKII and SAXS analysis of the holoenzyme. Cell, 123, 849–860.
7. Lars SM and Donald MB (2007). Role of Ca2+/calmodulin-dependent protein kinase (CaMK) in excitation–contraction coupling in the heart. Cardiovascular Research, 73(4), 631-640.
8. Alicia M, Leticia V and Cecilia MW (2007). Ca2+/calmodulin-dependent protein kinase: A key component in the contractile recovery from acidosis. Cardiovascular Research, 73(4), 648-656.
DNA damage actually causes gray hair
While many people attribute gray hair to age, a new, Japanese study has revealed that it really is a sign of stress. A cellular stress. This study was published in the June 12, 2009 issue of Cell journal.
Stress which damages DNA is referred to as genotoxic stress. In this case, when specialized cells, called melanocyte stem cells, (MSCs) are damaged, it ultimately results in a malfunction of those cells which express hair color. Genotoxic stress can deplete the MSCs in hair follicles that make the pigment-producing melanocytes. However, when exposed to the stress, the MSCs actually differentiate into mature melanocytes, as opposed to dying off. This means that if the genotoxic stress can be limited, graying may actually be halted.
Virtually all cells are exposed to some form of genotoxic stress, every day. However, cells are built to handle the stress and repair damaged DNA, and even work to prevent the damage from being passed on to daughter cells. However, once stem cells are irreparably damaged, they must be eliminated so that the quality of the stem cells pools can be maintained. Stresses on stem cell pools and genome maintenance failures are also thought responsible for the decline of tissue renewal capacity and the accelerated appearance of aging-related characteristics.
“We found that excessive genotoxic stress triggers differentiation of melanocyte stem cells,” said Emi Nishimura of Tokyo Medical and Dental University, who led the research team. Nishimura's team had previously traced graying hair to the gradual dying off of the stem cells that manufacture a continuous supply of new melanocytes, which are responsible for hair's youthful color. The study found that those specialized stem cells are not only lost, they also differentiate into fully committed pigment cells, and in the wrong place.
The study supports the idea that genome instability is a major factor in aging. It also supports the “stem cell aging hypothesis”, which states that DNA damage to stem cells can be attributed to many of the conditions that come with age.
“In this study, we discovered that hair graying, the most obvious aging phenotype, can be caused by the genomic damage response through stem cell differentiation, which suggests that physiological hair graying can be triggered by the accumulation of unavoidable DNA damage and DNA-damage response associated with aging through MSC differentiation,” the researchers wrote.
Stress which damages DNA is referred to as genotoxic stress. In this case, when specialized cells, called melanocyte stem cells, (MSCs) are damaged, it ultimately results in a malfunction of those cells which express hair color. Genotoxic stress can deplete the MSCs in hair follicles that make the pigment-producing melanocytes. However, when exposed to the stress, the MSCs actually differentiate into mature melanocytes, as opposed to dying off. This means that if the genotoxic stress can be limited, graying may actually be halted.
Virtually all cells are exposed to some form of genotoxic stress, every day. However, cells are built to handle the stress and repair damaged DNA, and even work to prevent the damage from being passed on to daughter cells. However, once stem cells are irreparably damaged, they must be eliminated so that the quality of the stem cells pools can be maintained. Stresses on stem cell pools and genome maintenance failures are also thought responsible for the decline of tissue renewal capacity and the accelerated appearance of aging-related characteristics.
“We found that excessive genotoxic stress triggers differentiation of melanocyte stem cells,” said Emi Nishimura of Tokyo Medical and Dental University, who led the research team. Nishimura's team had previously traced graying hair to the gradual dying off of the stem cells that manufacture a continuous supply of new melanocytes, which are responsible for hair's youthful color. The study found that those specialized stem cells are not only lost, they also differentiate into fully committed pigment cells, and in the wrong place.
The study supports the idea that genome instability is a major factor in aging. It also supports the “stem cell aging hypothesis”, which states that DNA damage to stem cells can be attributed to many of the conditions that come with age.
“In this study, we discovered that hair graying, the most obvious aging phenotype, can be caused by the genomic damage response through stem cell differentiation, which suggests that physiological hair graying can be triggered by the accumulation of unavoidable DNA damage and DNA-damage response associated with aging through MSC differentiation,” the researchers wrote.
Cell Penetrating or “Trojan” Peptides - CPP
Cell Penetrating or “Trojan” Peptides
During the last ten years it has been observed that a number of peptides and proteins are able to penetrate the cell membrane and enter the cell. Furthermore, it has been shown that even many cargo molecules that are covalently attached to these peptides will be translocated into the cell. Peptides that show the ability to translocate through the cell membrane are usually short peptides of less than 30 amino acids. Their only common feature appears to be that they are amphipathic and have a overall positive net charge. The exact mechanism of cell translocation is not known but appears to be receptor and energy independent, although in some cases their translocation can be partially mediated by endocytosis. The penetration into cells is usually rapid and of first-order, with half-times from 5 to 20 minutes [Zorko, M., and Langel, U., 2005].
The ability of a 60-amino acid polypeptide corresponding to the sequence of the Drosophila antennapedia gene homeobox to traverse across cell membranes of nerve cells and accumulate in the nuclei was first reported by Joiliot et al, in 1991. A shorter peptide coined penetratin is a 16 amino acids long peptide of cationic nature containing the sequence: RQIKIWFQNRRMKWKK. This sequence derives from helix 3 of the antennapedia complex [Thoren, P.E., et al., 2003; Fischer, P.M., et al., 2000] and is able to translocate through the plasma membrane to the cytosol and nucleus of living cells, both at 37 °C and 4 °C respectively.
Recently, methods have been developed for the delivery of exogenous proteins into living cells with the help of membrane-permeating carrier peptides derived from HIV-1 Tat (residues 48 to 60) and antennapedia (residues 43 to 58), penetratin [Derosssi, D., et al., 1998; Dunican D.J., et al., 2001]. The basic nature of these peptides and the locations of aromatic groups within their sequence allows these peptides to penetrate the cell membrane. Investigating a range of basic peptides, Futaki reported that a peptide containing eight arginine residues can efficiently translocate across the cell membrane [Futaki, S. 2002]. Recently, a chimeric peptide derived from galparan and transportan has been used as an effective peptide vector for biodelivery of BNA molecules [Pooga, Marcus., et.al., 1998]. Translocation of the penetratin peptide occurs even when it is coupled to hydrophilic molecules (e.g. phosphopeptides, oligonucleotides, peptidic nucleic acids, drugs, etc.) [Prochiantz, A., 1996]. Taking the “Illyad” a tale from the Greek mythologies as an example these cell-penetrating peptides (CPP) were also termed ‘Trojan’ peptides. Most of them are water-soluble peptides with a low lytic activity that can be used as vectors for cellular internalization of hydrophilic biomolecules and drugs [Lindgren, M., et al., 2000, Stephens, D.J., & Pepperkok, R. 2001]. Despite its broad application field, the internalization mechanism of the penetratin peptide has not been totally unraveled yet. It appears that a receptor or a transporter protein is not needed, as retro-enantio and retro-inverso analogs of penetratin are also internalized [Derossi, D., et al., 1996]. Presumably, cellular internalization of the penetratin peptide occurs via a direct interaction with the cell membrane [Prochiantz, A., 1996)].
Table 1 (below) contains a list of peptides that have been investigated for their ability to penetrate the cell. The potential to inhibit specific mRNA export pathways using cell-permeable peptides is shown in figure 1. Cell-penetrating peptide inhibitors are inhibiting their target proteins rapidly. In that sense they could be superior to other “functional knockout” approaches such as RNA interference (RNAi). RNAi prevents translation of a protein by destroying its mRNA; however, a long-lived protein will continue to be active long after its synthesis has stopped. The more rapidly a peptide affects RNA export, the more likely it is that the peptide directly (rather than indirectly) inhibits export of the target RNA. It is conceivable that designer inhibitory peptides based on the sequences of cell-penetrating peptides have the potential to allow for the generation of a mammalian cell tool kit that could parallel the temperature-sensitive mutant collection available to yeast geneticists [Moore and Rosbash, 2001].
Table 1: Peptides that translocate into the cell (Futaki, S. 2005)
Residues highlighted in dark bold blue indicate a positive charge where as the ones highlighted in bold red indicate negative charges.
Figure 1: The potential to inhibit specific mRNA export pathways with cell-permeable peptides. The major route of mRNA export from the nucleus may depend on interactions between the mRNA adaptor protein Aly/REF and the export receptor heterodimer TAP:p15, which in turn interacts with the nuclear pore complex. New inhibitors that couple cell-penetrating peptides with specific nuclear export signals reveal that some mRNAs use other adaptors and receptors. For example, there are two nuclear export pathways for c-fos mRNA. One pathway involves the adaptor protein HuR and the export receptor Trn2, whereas the other involves HuR, its two ligands (pp32 and APRIL) and the export receptor CRM1. [Melissa J. Moore and Michael Rosbash in SCIENCE VOL 294 p. 1841, 2001].
3D structures
Figure 2: Three-dimensional structure of the antennapedia homeodomain protein-DNA complex. (Protein Data Bank accession code 9ant). A: The protein is shown as the space-fill model whereas the DNA is displayed in ball-and-stick (one DNA strand) and stick mode (second DNA strand). B: Only the peptide corresponding to penetratin peptide is now displayed in the space-filling mode all other atoms are in the stick mode. It is apparent that the peptide is in close contact with the DNA molecule apparently binding to the major groove of the helix.
Figure 3: Three-dimensional solution structure of penetratin. (Protein Data Bank accession code 1kz0). Amino acid side chains of basic amino acid residues are highlighted in blue. The tryptophans are shown in purple. The primary structure of the peptides is also provided. All pictures were generated with the 3D mol viewer of Vector NT (version 6, Invitrogen, USA).
References
During the last ten years it has been observed that a number of peptides and proteins are able to penetrate the cell membrane and enter the cell. Furthermore, it has been shown that even many cargo molecules that are covalently attached to these peptides will be translocated into the cell. Peptides that show the ability to translocate through the cell membrane are usually short peptides of less than 30 amino acids. Their only common feature appears to be that they are amphipathic and have a overall positive net charge. The exact mechanism of cell translocation is not known but appears to be receptor and energy independent, although in some cases their translocation can be partially mediated by endocytosis. The penetration into cells is usually rapid and of first-order, with half-times from 5 to 20 minutes [Zorko, M., and Langel, U., 2005].
The ability of a 60-amino acid polypeptide corresponding to the sequence of the Drosophila antennapedia gene homeobox to traverse across cell membranes of nerve cells and accumulate in the nuclei was first reported by Joiliot et al, in 1991. A shorter peptide coined penetratin is a 16 amino acids long peptide of cationic nature containing the sequence: RQIKIWFQNRRMKWKK. This sequence derives from helix 3 of the antennapedia complex [Thoren, P.E., et al., 2003; Fischer, P.M., et al., 2000] and is able to translocate through the plasma membrane to the cytosol and nucleus of living cells, both at 37 °C and 4 °C respectively.
Recently, methods have been developed for the delivery of exogenous proteins into living cells with the help of membrane-permeating carrier peptides derived from HIV-1 Tat (residues 48 to 60) and antennapedia (residues 43 to 58), penetratin [Derosssi, D., et al., 1998; Dunican D.J., et al., 2001]. The basic nature of these peptides and the locations of aromatic groups within their sequence allows these peptides to penetrate the cell membrane. Investigating a range of basic peptides, Futaki reported that a peptide containing eight arginine residues can efficiently translocate across the cell membrane [Futaki, S. 2002]. Recently, a chimeric peptide derived from galparan and transportan has been used as an effective peptide vector for biodelivery of BNA molecules [Pooga, Marcus., et.al., 1998]. Translocation of the penetratin peptide occurs even when it is coupled to hydrophilic molecules (e.g. phosphopeptides, oligonucleotides, peptidic nucleic acids, drugs, etc.) [Prochiantz, A., 1996]. Taking the “Illyad” a tale from the Greek mythologies as an example these cell-penetrating peptides (CPP) were also termed ‘Trojan’ peptides. Most of them are water-soluble peptides with a low lytic activity that can be used as vectors for cellular internalization of hydrophilic biomolecules and drugs [Lindgren, M., et al., 2000, Stephens, D.J., & Pepperkok, R. 2001]. Despite its broad application field, the internalization mechanism of the penetratin peptide has not been totally unraveled yet. It appears that a receptor or a transporter protein is not needed, as retro-enantio and retro-inverso analogs of penetratin are also internalized [Derossi, D., et al., 1996]. Presumably, cellular internalization of the penetratin peptide occurs via a direct interaction with the cell membrane [Prochiantz, A., 1996)].
Table 1 (below) contains a list of peptides that have been investigated for their ability to penetrate the cell. The potential to inhibit specific mRNA export pathways using cell-permeable peptides is shown in figure 1. Cell-penetrating peptide inhibitors are inhibiting their target proteins rapidly. In that sense they could be superior to other “functional knockout” approaches such as RNA interference (RNAi). RNAi prevents translation of a protein by destroying its mRNA; however, a long-lived protein will continue to be active long after its synthesis has stopped. The more rapidly a peptide affects RNA export, the more likely it is that the peptide directly (rather than indirectly) inhibits export of the target RNA. It is conceivable that designer inhibitory peptides based on the sequences of cell-penetrating peptides have the potential to allow for the generation of a mammalian cell tool kit that could parallel the temperature-sensitive mutant collection available to yeast geneticists [Moore and Rosbash, 2001].
Table 1: Peptides that translocate into the cell (Futaki, S. 2005)
Residues highlighted in dark bold blue indicate a positive charge where as the ones highlighted in bold red indicate negative charges.
Figure 1: The potential to inhibit specific mRNA export pathways with cell-permeable peptides. The major route of mRNA export from the nucleus may depend on interactions between the mRNA adaptor protein Aly/REF and the export receptor heterodimer TAP:p15, which in turn interacts with the nuclear pore complex. New inhibitors that couple cell-penetrating peptides with specific nuclear export signals reveal that some mRNAs use other adaptors and receptors. For example, there are two nuclear export pathways for c-fos mRNA. One pathway involves the adaptor protein HuR and the export receptor Trn2, whereas the other involves HuR, its two ligands (pp32 and APRIL) and the export receptor CRM1. [Melissa J. Moore and Michael Rosbash in SCIENCE VOL 294 p. 1841, 2001].
3D structures
Figure 2: Three-dimensional structure of the antennapedia homeodomain protein-DNA complex. (Protein Data Bank accession code 9ant). A: The protein is shown as the space-fill model whereas the DNA is displayed in ball-and-stick (one DNA strand) and stick mode (second DNA strand). B: Only the peptide corresponding to penetratin peptide is now displayed in the space-filling mode all other atoms are in the stick mode. It is apparent that the peptide is in close contact with the DNA molecule apparently binding to the major groove of the helix.
Figure 3: Three-dimensional solution structure of penetratin. (Protein Data Bank accession code 1kz0). Amino acid side chains of basic amino acid residues are highlighted in blue. The tryptophans are shown in purple. The primary structure of the peptides is also provided. All pictures were generated with the 3D mol viewer of Vector NT (version 6, Invitrogen, USA).
References
- Derossi, D., Calvet, S., Trembleau, A., Brunissen, A., Chassaing, G. & Prochiantz, A. (1996) Cell internalization of the third helix of the Antennapedia homeodomain is receptor-independent. J. Biol. Chem. 271, 18188–18193.
- Derossi, D., Chassaing, G. & Prochiantz, A. (1998) Trojan peptides: the penetratin system for intracellular delivery. Trends Cell Biol. 8, 84–87.
- Dunican, D.J. & Doherty, P. (2001) Designing cell-permeant phosphopeptides to modulate intracellular signaling pathways. Biopolymers 60, 45–60.
- Fischer, P.M., Zhelev, N.Z., Wang, S., Melville, J.E., Fahraeus, R. & Lane, D.P. (2000) Structure-activity relationship of truncated and substituted analogues of the intracellular delivery vector Penetratin. J. Pept. Res. 55, 163–172
- Futaki, S. (2002) Arginine-rich peptides: potential for intracellular delivery of macromolecules and the mystery of the translocation mechanisms. Int. J. Pharm. 245, 1–7.
- Futaki, S. (2002) Membane-permeable arginine-rich peptides and the translocation mechanisms. Adv. Drug Del. Reviews 57, 547-558.
- Joliot, A., Pernelle, C., Deagostini-Bazin, H. & Prochiantz, A. (1991) Antennapedia homeobox peptide regulates neural morphogenesis. Proc. Natl Acad. Sci. USA 88, 1864–1868
- Lindgren, M., Hallbrink, M., Prochiantz, A. & Langel, U. Cell-penetrating peptides. (2000) Trends Pharmacol. Sci. 21, 99–103.
- Moore, M.J., and Rosbash, M., (2001) Cell biology. TAPing into mRNA export. Science 294, 1841-2.
- Pooga,M., Halbrink, M, Zorko, M, Langel, U., (1998) Cell Penetration by Transportan. FASEB Journal,12;67-77.
- Pooga M, Land T, Bartfai T, Langel U. (2001) PNA oligomers as tools for specific modulation of gene expression. Biomol Eng. 2001 Jun;17(6):183-92.
- Prochiantz, A. (1996) Getting hydrophilic compounds into cells: lessons from homeopeptides. Curr. Opin. Neurobiol. 6, 629–634.
- Prochiantz, A. (1996) Getting hydrophilic compounds into cells: lessons from homeopeptides. Curr. Opin. Neurobiol. 6, 629–634.
- Saalik P, Elmquist A, Hansen M, Padari K, Saar K, Viht K, Langel U, Pooga M. (2004) Protein cargo delivery properties of cell-penetrating peptides. A comparative study. Bioconjug Chem. Nov-Dec;15(6):1246-53.
- Stephens, D.J., & Pepperkok, R. The many ways to cross the plasma membrane. (2001) Proc. Natl Acad. Sci. USA 98, 4295–4298
- Thorén, P.E., Persson, D., Isakson, P., Goksör, M., Önfelt, A. & Nordén, B. (2003) Uptake of analogs of penetratin, Tat (48–60) and oligoarginine in live cells. Bioch. Biophys. Res. Comm. 307, 100–107.
- Zorko, M. and Langel, U., (2005) Cell-penetrating peptides: mechanism and kinetics of cargo delivery. Adv. Drug Del. Reviews 57, 529-545.
Thursday, June 25, 2009
Band 3 Protein Fragments
Definition
Band 3 protein fragments are phylogenetically preserved transport peptides located on the organelle membranes especially the erythrocyte membrane where they mediate anion exchange1.
Discovery
Band 3 peptides were originally identified following SDS-gel electrophoresis of erythrocyte cell membrane. The large third band on the gel turned out to be the peptide. Hence the name Band 31.
Classification
Band 3 proteins are members of anion-exchange (AE) family of proteins2. AE proteins are encoded by a multigene family that has atleast three genes, AE1, AE2, AE3 and several splicioforms2. They are all expressed by most cells, e.g., erythrocytes, cardiomyocytes.
Structural Characteristics
Band 3 fragments have two functional domains.The integral domain mediates a 1:1 exchange of inorganic anions across the membrane, whereas the cytoplasmic domain provides binding sites for cytoskeletal proteins, glycolytic enzymes, and hemoglobin3. Activation of Band 3 fragments occurs through tyrosine phosphorylation4.
Mode of action
Band 3 peptide is bound to the erythrocyte membrane5. Its N-terminal region protrudes from the main body towards the red cell cytoplasm allowing it to interact with various membrane bound and cytoplasmic red cell components such as glycolytic enzymes including aldolase, glyceraldehyde-3-phosphate dehydrogenase and phosphofructokinase as well as other membrane components such as ankyrin and protein 4.15,6. Recently it has been found that Band 3 also binds to Hemoglobin. Interaction of Band 3 with these proteins exerts several changes in the cells for example lowering oxygen affinity of Hemoglobin5.
Functions
Band 3 fragments are involved in the anion-exchange across the plasma membrane on a one-for-one basis. This is crucial for CO2 uptake by the red cell and conversion into a proton and a bicarbonate ion that is then extruded from the cell by the band 3 molecule2. Band 3 serves as a physical linkage between the plasma membrane and the underlying membrane skeleton via binding with ankyrin and protein 4.15. This appears to prevent membrane surface loss. A spliced variant of Band 3 nAE1 regulates pH in cardioventricular myocytes through anion-exchange2. Band 3 is also an allosteric regulator of Heamoglobin as it binds to Hb and decreases its affinity for oxygen5. Other functions of Band 3 fragments include maintenance of cell volume and osmotic homeostasis, red cell aging, IgG binding and cellular removal7. Band 3 alterations are implicated in neurological diseases such as familial paroxysmal dyskinesia, idiopathic generalized epilepsies, and neuro- or choreoacanthocytosis7.
References
1.Hunter M (1977). Human erythrocyte anion permeabilities measured under conditions of net charge transfer. J Physiol, 268 (1): 35–49.
2.Richards SM, Jaconi ME, Vassort G and Puceat M (1999). A spliced variant of AE1 gene encodes a truncated form of Band 3 in heart: the predominant anion exchanger in ventricular myocytes.
3.Jonathan DG, Lin W and Michael JAT (1998). Complementation studies with co-expressed fragments of human red cell band 3 (AE1): the assembly of the anion-transport domain in Xenopus oocytes and a cell-free translation system. Biochem. J., 332, 161-171.
4.Yannoukakos D, Vasseur C, Piau JP, Wajcman H, Bursaux E (1991). Phosphorylation sites in human erythrocyte band 3 protein. Biochim. Biophys. Acta, 1061, 253-266.
5.Yuxun Z, Lois RM, Jill F, Orah P and James MM (2003), Human Erythrocyte Membrane Band 3 Protein Influences Hemoglobin Cooperativity: Possible effect on oxygen transport. J. Biol. Chem., 278, 41, 39565-39571.
6.Chambers EJ, Askin D, Bloomberg GB, et al. (1998). Studies on the structure of a transmembrane region and a cytoplasmic loop of the human red cell anion exchanger (band 3, AE1), Biochem. Soc. Trans., 26 (3): 516–20.
7.Kay MM (2004). Band 3 and its alterations in health and disease. Cell Mol Bio, 52, 117-38.
Band 3 protein fragments are phylogenetically preserved transport peptides located on the organelle membranes especially the erythrocyte membrane where they mediate anion exchange1.
Discovery
Band 3 peptides were originally identified following SDS-gel electrophoresis of erythrocyte cell membrane. The large third band on the gel turned out to be the peptide. Hence the name Band 31.
Classification
Band 3 proteins are members of anion-exchange (AE) family of proteins2. AE proteins are encoded by a multigene family that has atleast three genes, AE1, AE2, AE3 and several splicioforms2. They are all expressed by most cells, e.g., erythrocytes, cardiomyocytes.
Structural Characteristics
Band 3 fragments have two functional domains.The integral domain mediates a 1:1 exchange of inorganic anions across the membrane, whereas the cytoplasmic domain provides binding sites for cytoskeletal proteins, glycolytic enzymes, and hemoglobin3. Activation of Band 3 fragments occurs through tyrosine phosphorylation4.
Mode of action
Band 3 peptide is bound to the erythrocyte membrane5. Its N-terminal region protrudes from the main body towards the red cell cytoplasm allowing it to interact with various membrane bound and cytoplasmic red cell components such as glycolytic enzymes including aldolase, glyceraldehyde-3-phosphate dehydrogenase and phosphofructokinase as well as other membrane components such as ankyrin and protein 4.15,6. Recently it has been found that Band 3 also binds to Hemoglobin. Interaction of Band 3 with these proteins exerts several changes in the cells for example lowering oxygen affinity of Hemoglobin5.
Functions
Band 3 fragments are involved in the anion-exchange across the plasma membrane on a one-for-one basis. This is crucial for CO2 uptake by the red cell and conversion into a proton and a bicarbonate ion that is then extruded from the cell by the band 3 molecule2. Band 3 serves as a physical linkage between the plasma membrane and the underlying membrane skeleton via binding with ankyrin and protein 4.15. This appears to prevent membrane surface loss. A spliced variant of Band 3 nAE1 regulates pH in cardioventricular myocytes through anion-exchange2. Band 3 is also an allosteric regulator of Heamoglobin as it binds to Hb and decreases its affinity for oxygen5. Other functions of Band 3 fragments include maintenance of cell volume and osmotic homeostasis, red cell aging, IgG binding and cellular removal7. Band 3 alterations are implicated in neurological diseases such as familial paroxysmal dyskinesia, idiopathic generalized epilepsies, and neuro- or choreoacanthocytosis7.
References
1.Hunter M (1977). Human erythrocyte anion permeabilities measured under conditions of net charge transfer. J Physiol, 268 (1): 35–49.
2.Richards SM, Jaconi ME, Vassort G and Puceat M (1999). A spliced variant of AE1 gene encodes a truncated form of Band 3 in heart: the predominant anion exchanger in ventricular myocytes.
3.Jonathan DG, Lin W and Michael JAT (1998). Complementation studies with co-expressed fragments of human red cell band 3 (AE1): the assembly of the anion-transport domain in Xenopus oocytes and a cell-free translation system. Biochem. J., 332, 161-171.
4.Yannoukakos D, Vasseur C, Piau JP, Wajcman H, Bursaux E (1991). Phosphorylation sites in human erythrocyte band 3 protein. Biochim. Biophys. Acta, 1061, 253-266.
5.Yuxun Z, Lois RM, Jill F, Orah P and James MM (2003), Human Erythrocyte Membrane Band 3 Protein Influences Hemoglobin Cooperativity: Possible effect on oxygen transport. J. Biol. Chem., 278, 41, 39565-39571.
6.Chambers EJ, Askin D, Bloomberg GB, et al. (1998). Studies on the structure of a transmembrane region and a cytoplasmic loop of the human red cell anion exchanger (band 3, AE1), Biochem. Soc. Trans., 26 (3): 516–20.
7.Kay MM (2004). Band 3 and its alterations in health and disease. Cell Mol Bio, 52, 117-38.
BAM (Bovine Adrenal Medulla) Peptides
Definition
Bovine adrenal medulla (BAM) peptides are peptides secreted in the adrenal gland that exhibit potent opioid activity1.
Discovery
BAM peptides were first purified from bovine adrenal medulla and it was found that upon their trypsinization they can yield the other enkephalin peptide-Met Enkephalin2.
Classification
BAM peptides are cleavage products of the opioid peptide, pro-enkephalin. There are atleast three different BAM peptides that have been identified so far: BAM 12P, 20P and 22P3.
Structural Characteristics
BAM 22P is a docosa peptide that is a cleavage product of pro-enkephalin. BAM 20P and BAM 12P are C-terminal shortened versions of BAM 22P2.
Mode of action
BAM peptides normally bind to opioid receptors on neural cells and trigger a response. For instance, BAM22P binds to G-Protein coupled sensory neuro receptors and opioid receptors which when activated trigger a series of pain signals4.
Functions
BAM peptides mainly expressed in the central nervous system have potent opioid activity. BAM22P inhibits reflex bladder action, induces analgesic response in mice and also exerts a protective action during stress such as shock or injury4. The exact functions of other BAM peptides remain unclear.
References
1.Swain MG, MacArthur L, Vergalla J and Jones EA (1994). Adrenal secretion of BAM-22P, a potent opioid peptide, is enhanced in rats with acute cholestasis. Am J Physiol Gastrointest Liver Physiol , 266, G201-G205.
2.Mizuno K, Minamino N, Kangawa K and Matsuo H (1980). A new family of endogenous “big” met-enkephalins from bovine adrenal medulla: purification and structure of docosa- (BAM-22P) and eicosapeptide (BAM-20P) with very potent opiate activity. Biochem. and Biophy. Res. Comm., 47, 1283-90.
3.Book: Frank M and Klaus V, Molecular and Cellular Exercise Physiology.
4.Yanguo H, Peifang D, Jianping J and Xueai Z (2004). Dual effects of intrathecal BAM22 on nociceptive responses in acute and persistent pain–potential function of a novel receptor. Br J Pharmacol, 141(3): 423–430.
Bovine adrenal medulla (BAM) peptides are peptides secreted in the adrenal gland that exhibit potent opioid activity1.
Discovery
BAM peptides were first purified from bovine adrenal medulla and it was found that upon their trypsinization they can yield the other enkephalin peptide-Met Enkephalin2.
Classification
BAM peptides are cleavage products of the opioid peptide, pro-enkephalin. There are atleast three different BAM peptides that have been identified so far: BAM 12P, 20P and 22P3.
Structural Characteristics
BAM 22P is a docosa peptide that is a cleavage product of pro-enkephalin. BAM 20P and BAM 12P are C-terminal shortened versions of BAM 22P2.
Mode of action
BAM peptides normally bind to opioid receptors on neural cells and trigger a response. For instance, BAM22P binds to G-Protein coupled sensory neuro receptors and opioid receptors which when activated trigger a series of pain signals4.
Functions
BAM peptides mainly expressed in the central nervous system have potent opioid activity. BAM22P inhibits reflex bladder action, induces analgesic response in mice and also exerts a protective action during stress such as shock or injury4. The exact functions of other BAM peptides remain unclear.
References
1.Swain MG, MacArthur L, Vergalla J and Jones EA (1994). Adrenal secretion of BAM-22P, a potent opioid peptide, is enhanced in rats with acute cholestasis. Am J Physiol Gastrointest Liver Physiol , 266, G201-G205.
2.Mizuno K, Minamino N, Kangawa K and Matsuo H (1980). A new family of endogenous “big” met-enkephalins from bovine adrenal medulla: purification and structure of docosa- (BAM-22P) and eicosapeptide (BAM-20P) with very potent opiate activity. Biochem. and Biophy. Res. Comm., 47, 1283-90.
3.Book: Frank M and Klaus V, Molecular and Cellular Exercise Physiology.
4.Yanguo H, Peifang D, Jianping J and Xueai Z (2004). Dual effects of intrathecal BAM22 on nociceptive responses in acute and persistent pain–potential function of a novel receptor. Br J Pharmacol, 141(3): 423–430.
Brain Natriuretic Peptides (BNP)
Definition
Brain natriuretic peptide (BNP) is a 32 amino acid polypeptide that is secreted by the ventricles of the heart in response to stretching of heart muscles1.
Discovery
BNP was first discovered in porcine brain extracts based on its resemblance to atrial natriuretic peptide (a hormone secreted by mammalian atria) 1.
Classification
BNP belongs to the natriuretic family of peptides that contain three structurally related paracrine factors: Atrial, Brain and C-type natruirectic peptides2. Both atrial and brain natriuretic peptides are secreted in the atria and ventricles of the heart while C-type peptide is secreted in the bone2. BNP is co-secreted along with a 76 amino acid N-terminal fragment (NT-proBNP) which is biologically inactive3.
Structural Characteristics
BNP is a horseshoe-shaped 32 amino acid peptide that is held by a disulphide bridge formed between amino acids 10 and 264. It is produced by cleavage of large precursors- prepro and prohormones4.
Mode of action
BNP activates a transmembrane guanylyl cyclase, natriuretic peptide receptor-A (NPR-A). Activated NPR-A in turn produces the second messanger cGMP that triggers effectors that mediate its cardiac functions5,6.
Functions
BNP similar to ANP decreases systemic vascular resistance and central venous pressure resulting in a decrease in cardiac output and blood volume7. Both BNP and NT-proBNP levels in the blood are used for screening, diagnosis of acute congestive heart failure (CHF) and may be useful to establish prognosis in heart failure, as both markers are typically higher in patients with worse outcome8. The plasma concentrations of both BNP and NT-proBNP are also typically increased in patients with asymptomatic or symptomatic left ventricular dysfunction8.
BNP plays a very important role in prognostication of millions of diabetics9. It has an improtant role in prognostication of heart surgery patients10. It has been shown that combining BNP with other tools like ICG can improve early diagnosis of heart failure and advance prevention strategies11. BNP can be elevated in renal failure12. The BNP test is used as an aid in the diagnosis and assessment of severity of congestive heart failure (also referred to as heart failure)13.
References
1.Tetsuji S, Kenji K, Naoto M and Hisayuki M (1988), A new natriuretic peptide in porcine brain, Nature, 332, 78-81.
2.Potter LR, Yoder AR, Flora DR, Antos LK, Dickey DM (2009), Natruiretic peptides: their structures, receptors, physiologic functions and therapeutic applications, Handb Exp Pharmacol, 191, 341-66.
3.Bibbins-Domingo K, Gupta R, Na B, Wu AH, Schiller NB, Whooley MA (2007). "N-terminal fragment of the prohormone brain-type natriuretic peptide (NT-proBNP), cardiovascular events, and mortality in patients with stable coronary heart disease". JAMA 297 (2): 169–76.
4.Brandt I, Lambeir AM, Ketelsleger JM, Vanderheyden M, Scharpé S and Meest ID, (2006), Dipeptidyl-peptidase IV converts intact B-type natriuretic peptide into its des-SerPro form. Clin. Chem, 52(1): 82-87.
5.David G. Lowe (1992), Human natriuretic peptide receptor-A guanylyl cyclase is self-associated prior to hormone binding, Biochemistry, 31 (43), pp 10421–10425.
6.Jun S, Peter M. S and Harvey R. W, (2005), Differential Effects of cGMP Produced by Soluble and Particulate Guanylyl Cyclase on Mouse Ventricular Myocytes, Experimental Biology and Medicine 230:242-250.
7.Bhalla V, Willis S, Maisel AS (2004). "B-type natriuretic peptide: the level and the drug--partners in the diagnosis of congestive heart failure". Congest Heart Fail 10(1 Suppl 1): 3–27.
8.Atisha D, Bhalla MA, Morrison LK, Felicio L, Clopton P, Gardetto N, Kazanegra R, Chiu A, Maisel AS (2004). "A prospective study in search of an optimal B-natriuretic peptide level to screen patients for cardiac dysfunction". Am. Heart J. 148 (3): 518–23.
9.Bhalla MA, Chiang A, Epshteyn VA, Kazanegra R, Bhalla V, Clopton P, Krishnaswamy P, Morrison LK, Chiu A, Gardetto N, Mudaliar S, Edelman SV, Henry RR, Maisel AS (2004). "Prognostic role of B-type natriuretic peptide levels in patients with type 2 diabetes mellitus". J. Am. Coll. Cardiol. 44 (5): 1047–52.
10.Lee CY, Burnett JC Jr. (2007), Natruiteric peptides and therapeutic applications, Heart Fail Rev, 12 (2), 131-42
11.Castellanos LR, Bhalla V, Isakson S, Daniels LB, Bhalla MA, Lin JP, Clopton P, Gardetto N, Hoshino M, Chiu A, Fitzgerald R, Maisel AS (2009). "B-type natriuretic peptide and impedance cardiography at the time of routine echocardiography predict subsequent heart failure events". J. Card. Fail. 15 (1): 41–7.
12.Bhalla V, Maisel AS (June 2004). "B-type natriuretic peptide. A biomarker for all the right reasons". Ital Heart J 5 (6): 417–20.
13.Fitzgerald RL, Cremo R, Gardetto N, Chiu A, Clopton P, Bhalla V, Maisel AS (2005). "Effect of nesiritide in combination with standard therapy on serum concentrations of natriuretic peptides in patients admitted for decompensated congestive heart failure". Am. Heart J. 150 (3): 471–7.
Brain natriuretic peptide (BNP) is a 32 amino acid polypeptide that is secreted by the ventricles of the heart in response to stretching of heart muscles1.
Discovery
BNP was first discovered in porcine brain extracts based on its resemblance to atrial natriuretic peptide (a hormone secreted by mammalian atria) 1.
Classification
BNP belongs to the natriuretic family of peptides that contain three structurally related paracrine factors: Atrial, Brain and C-type natruirectic peptides2. Both atrial and brain natriuretic peptides are secreted in the atria and ventricles of the heart while C-type peptide is secreted in the bone2. BNP is co-secreted along with a 76 amino acid N-terminal fragment (NT-proBNP) which is biologically inactive3.
Structural Characteristics
BNP is a horseshoe-shaped 32 amino acid peptide that is held by a disulphide bridge formed between amino acids 10 and 264. It is produced by cleavage of large precursors- prepro and prohormones4.
Mode of action
BNP activates a transmembrane guanylyl cyclase, natriuretic peptide receptor-A (NPR-A). Activated NPR-A in turn produces the second messanger cGMP that triggers effectors that mediate its cardiac functions5,6.
Functions
BNP similar to ANP decreases systemic vascular resistance and central venous pressure resulting in a decrease in cardiac output and blood volume7. Both BNP and NT-proBNP levels in the blood are used for screening, diagnosis of acute congestive heart failure (CHF) and may be useful to establish prognosis in heart failure, as both markers are typically higher in patients with worse outcome8. The plasma concentrations of both BNP and NT-proBNP are also typically increased in patients with asymptomatic or symptomatic left ventricular dysfunction8.
BNP plays a very important role in prognostication of millions of diabetics9. It has an improtant role in prognostication of heart surgery patients10. It has been shown that combining BNP with other tools like ICG can improve early diagnosis of heart failure and advance prevention strategies11. BNP can be elevated in renal failure12. The BNP test is used as an aid in the diagnosis and assessment of severity of congestive heart failure (also referred to as heart failure)13.
References
1.Tetsuji S, Kenji K, Naoto M and Hisayuki M (1988), A new natriuretic peptide in porcine brain, Nature, 332, 78-81.
2.Potter LR, Yoder AR, Flora DR, Antos LK, Dickey DM (2009), Natruiretic peptides: their structures, receptors, physiologic functions and therapeutic applications, Handb Exp Pharmacol, 191, 341-66.
3.Bibbins-Domingo K, Gupta R, Na B, Wu AH, Schiller NB, Whooley MA (2007). "N-terminal fragment of the prohormone brain-type natriuretic peptide (NT-proBNP), cardiovascular events, and mortality in patients with stable coronary heart disease". JAMA 297 (2): 169–76.
4.Brandt I, Lambeir AM, Ketelsleger JM, Vanderheyden M, Scharpé S and Meest ID, (2006), Dipeptidyl-peptidase IV converts intact B-type natriuretic peptide into its des-SerPro form. Clin. Chem, 52(1): 82-87.
5.David G. Lowe (1992), Human natriuretic peptide receptor-A guanylyl cyclase is self-associated prior to hormone binding, Biochemistry, 31 (43), pp 10421–10425.
6.Jun S, Peter M. S and Harvey R. W, (2005), Differential Effects of cGMP Produced by Soluble and Particulate Guanylyl Cyclase on Mouse Ventricular Myocytes, Experimental Biology and Medicine 230:242-250.
7.Bhalla V, Willis S, Maisel AS (2004). "B-type natriuretic peptide: the level and the drug--partners in the diagnosis of congestive heart failure". Congest Heart Fail 10(1 Suppl 1): 3–27.
8.Atisha D, Bhalla MA, Morrison LK, Felicio L, Clopton P, Gardetto N, Kazanegra R, Chiu A, Maisel AS (2004). "A prospective study in search of an optimal B-natriuretic peptide level to screen patients for cardiac dysfunction". Am. Heart J. 148 (3): 518–23.
9.Bhalla MA, Chiang A, Epshteyn VA, Kazanegra R, Bhalla V, Clopton P, Krishnaswamy P, Morrison LK, Chiu A, Gardetto N, Mudaliar S, Edelman SV, Henry RR, Maisel AS (2004). "Prognostic role of B-type natriuretic peptide levels in patients with type 2 diabetes mellitus". J. Am. Coll. Cardiol. 44 (5): 1047–52.
10.Lee CY, Burnett JC Jr. (2007), Natruiteric peptides and therapeutic applications, Heart Fail Rev, 12 (2), 131-42
11.Castellanos LR, Bhalla V, Isakson S, Daniels LB, Bhalla MA, Lin JP, Clopton P, Gardetto N, Hoshino M, Chiu A, Fitzgerald R, Maisel AS (2009). "B-type natriuretic peptide and impedance cardiography at the time of routine echocardiography predict subsequent heart failure events". J. Card. Fail. 15 (1): 41–7.
12.Bhalla V, Maisel AS (June 2004). "B-type natriuretic peptide. A biomarker for all the right reasons". Ital Heart J 5 (6): 417–20.
13.Fitzgerald RL, Cremo R, Gardetto N, Chiu A, Clopton P, Bhalla V, Maisel AS (2005). "Effect of nesiritide in combination with standard therapy on serum concentrations of natriuretic peptides in patients admitted for decompensated congestive heart failure". Am. Heart J. 150 (3): 471–7.
Bag Cell Peptides
Definition
Bag cell peptides (BCPs) are a class of small neuropeptides secreted by the bag cell neurons in the marine mollusk Aplysia1. They trigger a series of reproductive behavior in this mollusk that finally culminates in egg-laying1.
Discovery
BCPs were originally identified in the bag cell extracts of abdominal ganglion of mature Aplysia that were obtained in Venice, CA2. They were isolated based on their ability to cause bag cell excitation2.
Classification
Bag cell specific gene that encodes for the precursor form of the egg laying hormone also contains sequences that encode several small BCPs: a-BCP, b-BCP, g-BCP2, d-BCP3,4 and e-BCP5.
Structural Characteristics
a-BCP is a 9 amino acid (Ala-Pro-Arg-Leu-Arg-Phe-Tyr-Ser-Leu) neuro tramsmittor whose Phe6-Tyr7 is necessary and sufficient for its function6. It does not undergo any NH2 or COOH modifications. b-BCP (Arg-Leu-Arg-Phe-His)7 and g-BCP are five amino acid peptides while d-BCP and e-BCP contain 39 and 19 amino acid residues respectively5.
Mode of action
Excitation of Bag Cell neurons triggers an afterdischarge response that results in the secretion of BCPs8. In addition, once the afterdischarge is underway, peptide release occurs in response to both calcium influx from the extracellular space and calcium release from intracellular stores8. Upon secretion the BCPs are packaged into discrete vescicles that are distributed throughout the central nervous system of Aplysia where they exert their functions4.
Functions
Release of egg-laying hormone and BCPs mediates the egg laying behavior in Aplysia4. Egg laying behavior is a result of several neuronal responses that include burst augmentation of cell R15, prolonged excitation of left lower quadrant neurons and inhibition of left upper quadrant neurons. BCPs have several functions in the bag cells2. a-BCP inhibits the left upper quardant cells, b-BCP excites L1, R1 and bag cells in the abdominal ganglion of Aplysia, g-BCP excites bag cells and d-BCP stimulates calcium release from the mitochondria5. This elecrophysiological chnages to the bag cells by the BCPs and other hormones culminates in egg-laying.
References
1.Rothman BS, Weir G, Dudek FE (1983a). Egg-laying hormone: direct action on the ovitestis Aplysia. Gen Comp Endocrinol, 52,134-141.
2.Rothman BS, Mayeri E, Brown RO, Yuan PM, Shively JE (1983b). Primary structure and neuronal effects of alpha-bag cell peptide, a second candidate neurotransmitter encoded by a single gene in bag cell neurons of Aplysia. Proc Natl Acad Sci, 80, 5753-5757.
3.Fisher JM, Sossin W, Newcomb R, Scheller RH (1988). Multiple neuropeptides derived from a common precursor are differentially packaged and transported. Cell, 54,813-822.
4.Hatcher NG, Sweedler JV (2008). Aplysia bag cells function as a distributed neurosecretory network. J. Neurophysiol.. 99, 333-343.
5.Gregg TN, Sherry DP, and James EB (1989). The Egg-Laying Hormone Family: Precursors, Products, and Functions. Bio Bull, 177, 210-217.
6.Owens DF, Menon JG, Rotham BS (1992). Structure-activity relationship of the neurotransmitter alpha-bag cell peptide on aplysia LUQ neurons: implications regarding its inactivation in the extra cellular space. J of Neurobiology, 6, 650-70.
7.Rothman BS, Dekruyfft S, Talebian SM, Menon JG, Squire CR, Yehll CH, and Lee TD (1992). Aplysia Peptide Neurotransmitters & Bag Cell Peptide, Phe-Met-Arg-Phe- amide, and Small Cardioexcitatory Peptide B Are Rapid Degraded by a Leucine Aminopeptidase-like Activity in Hemolymph, J Biol. Chem., 287, 35, 25135-140.
8.Karen JL, Ronald JK, John AC and Leonard KK (2004). Hyperosmotic media inhibit voltage-dependent calcium influx and peptide release in Aplysia neurons, J Memb. Biol., Vol 128, 41-52.
Bag cell peptides (BCPs) are a class of small neuropeptides secreted by the bag cell neurons in the marine mollusk Aplysia1. They trigger a series of reproductive behavior in this mollusk that finally culminates in egg-laying1.
Discovery
BCPs were originally identified in the bag cell extracts of abdominal ganglion of mature Aplysia that were obtained in Venice, CA2. They were isolated based on their ability to cause bag cell excitation2.
Classification
Bag cell specific gene that encodes for the precursor form of the egg laying hormone also contains sequences that encode several small BCPs: a-BCP, b-BCP, g-BCP2, d-BCP3,4 and e-BCP5.
Structural Characteristics
a-BCP is a 9 amino acid (Ala-Pro-Arg-Leu-Arg-Phe-Tyr-Ser-Leu) neuro tramsmittor whose Phe6-Tyr7 is necessary and sufficient for its function6. It does not undergo any NH2 or COOH modifications. b-BCP (Arg-Leu-Arg-Phe-His)7 and g-BCP are five amino acid peptides while d-BCP and e-BCP contain 39 and 19 amino acid residues respectively5.
Mode of action
Excitation of Bag Cell neurons triggers an afterdischarge response that results in the secretion of BCPs8. In addition, once the afterdischarge is underway, peptide release occurs in response to both calcium influx from the extracellular space and calcium release from intracellular stores8. Upon secretion the BCPs are packaged into discrete vescicles that are distributed throughout the central nervous system of Aplysia where they exert their functions4.
Functions
Release of egg-laying hormone and BCPs mediates the egg laying behavior in Aplysia4. Egg laying behavior is a result of several neuronal responses that include burst augmentation of cell R15, prolonged excitation of left lower quadrant neurons and inhibition of left upper quadrant neurons. BCPs have several functions in the bag cells2. a-BCP inhibits the left upper quardant cells, b-BCP excites L1, R1 and bag cells in the abdominal ganglion of Aplysia, g-BCP excites bag cells and d-BCP stimulates calcium release from the mitochondria5. This elecrophysiological chnages to the bag cells by the BCPs and other hormones culminates in egg-laying.
References
1.Rothman BS, Weir G, Dudek FE (1983a). Egg-laying hormone: direct action on the ovitestis Aplysia. Gen Comp Endocrinol, 52,134-141.
2.Rothman BS, Mayeri E, Brown RO, Yuan PM, Shively JE (1983b). Primary structure and neuronal effects of alpha-bag cell peptide, a second candidate neurotransmitter encoded by a single gene in bag cell neurons of Aplysia. Proc Natl Acad Sci, 80, 5753-5757.
3.Fisher JM, Sossin W, Newcomb R, Scheller RH (1988). Multiple neuropeptides derived from a common precursor are differentially packaged and transported. Cell, 54,813-822.
4.Hatcher NG, Sweedler JV (2008). Aplysia bag cells function as a distributed neurosecretory network. J. Neurophysiol.. 99, 333-343.
5.Gregg TN, Sherry DP, and James EB (1989). The Egg-Laying Hormone Family: Precursors, Products, and Functions. Bio Bull, 177, 210-217.
6.Owens DF, Menon JG, Rotham BS (1992). Structure-activity relationship of the neurotransmitter alpha-bag cell peptide on aplysia LUQ neurons: implications regarding its inactivation in the extra cellular space. J of Neurobiology, 6, 650-70.
7.Rothman BS, Dekruyfft S, Talebian SM, Menon JG, Squire CR, Yehll CH, and Lee TD (1992). Aplysia Peptide Neurotransmitters & Bag Cell Peptide, Phe-Met-Arg-Phe- amide, and Small Cardioexcitatory Peptide B Are Rapid Degraded by a Leucine Aminopeptidase-like Activity in Hemolymph, J Biol. Chem., 287, 35, 25135-140.
8.Karen JL, Ronald JK, John AC and Leonard KK (2004). Hyperosmotic media inhibit voltage-dependent calcium influx and peptide release in Aplysia neurons, J Memb. Biol., Vol 128, 41-52.
Basic Fibroblast Growth Factor (FGF) Inhibitory Peptides
Definition
Basic fibroblast growth factor (bFGF) is a potent heparin binding growth factor that promotes proliferation, migration and differentiation of mesenchymal and neuro ectodermal cells. It exerts its functions by binding to bFGF receptor on cell membranes1. bFGF inhibitory peptides are short peptides that inhibit bFGF receptor binding and its biological function1.
Discovery
bFGF inhibitory peptides were isolated from a phage epitope library using monoclonal antibodies raised against human recombinant bFGF. These monoclonal antibodies were found to efficiently block bFGF binding to its receptors1.
Classification
So far three bFGF inhibitory peptides have been characterized: bFGF inhibitory peptide, bFGF 119-126 and bFGF inhibitory peptide II1.
Structural Characteristics
The inhibitory peptides share a consensus sequence Pro-(Pro/Ser)-Gly-His-(Tyr/Phe)-Lys that corresponds to bFGF sequences at 13-18 and 120-1251.
Mode of action
bFGF 119-126 inhibits the dimerization and binding of bFGF receptors1. bFGF inhibitory peptide blocks the binding of bFGF-induced proliferation of vascular endothelial cells2,3. bFGF inhibitory peptide II has conformational similarity to the putative receptor binding domain of bFGF and hence blocks bFGF binding to its receptor4.
Functions
Inhibition or de-regulation of bFGF leads to pathological conditions involving angiogenesis and tumor growth2. bFGF inhibitory peptide II suppresses the proliferation of human glioma cells and is a potential new product for the treatment of malignant glioma4.
References
1.Avener Y, David A, Michal S, Janet L. G, Yehudit H, Shmuel C, David G, and Ephraim KK (1993). Isolation of peptides that inhibit binding of basic fibroblast growth factor to its receptor from a random phage-epitope library. Proc. Natl. Acad. Sci. USA, 90,10643-10647.
2.Luo J and Miller MW (1996). Ethanol inhibits bFGF-mediated proliferation of C6 glioma cells. J. Neurochem., 67, 1448-1456.
3.Torsten G, Hae YS, Gerald AM, and Ulrich P (2002). Shear Stress-induced Release of Basic Fibroblast Growth Factor from Endothelial Cells Is Mediated by Matrix Interaction via Integrin aVß3. J. Biol. Chem., 277, 23453 – 23458.
4.Gloe T, Sohn HY, Gerald AM, and Ulrich P (2002). Shear-stress induced release of bFGF from endothelial cells is mediated by matrix interaction via integrin alpha V beta 3. J. Biol. Chem., 277, 23453.
Basic fibroblast growth factor (bFGF) is a potent heparin binding growth factor that promotes proliferation, migration and differentiation of mesenchymal and neuro ectodermal cells. It exerts its functions by binding to bFGF receptor on cell membranes1. bFGF inhibitory peptides are short peptides that inhibit bFGF receptor binding and its biological function1.
Discovery
bFGF inhibitory peptides were isolated from a phage epitope library using monoclonal antibodies raised against human recombinant bFGF. These monoclonal antibodies were found to efficiently block bFGF binding to its receptors1.
Classification
So far three bFGF inhibitory peptides have been characterized: bFGF inhibitory peptide, bFGF 119-126 and bFGF inhibitory peptide II1.
Structural Characteristics
The inhibitory peptides share a consensus sequence Pro-(Pro/Ser)-Gly-His-(Tyr/Phe)-Lys that corresponds to bFGF sequences at 13-18 and 120-1251.
Mode of action
bFGF 119-126 inhibits the dimerization and binding of bFGF receptors1. bFGF inhibitory peptide blocks the binding of bFGF-induced proliferation of vascular endothelial cells2,3. bFGF inhibitory peptide II has conformational similarity to the putative receptor binding domain of bFGF and hence blocks bFGF binding to its receptor4.
Functions
Inhibition or de-regulation of bFGF leads to pathological conditions involving angiogenesis and tumor growth2. bFGF inhibitory peptide II suppresses the proliferation of human glioma cells and is a potential new product for the treatment of malignant glioma4.
References
1.Avener Y, David A, Michal S, Janet L. G, Yehudit H, Shmuel C, David G, and Ephraim KK (1993). Isolation of peptides that inhibit binding of basic fibroblast growth factor to its receptor from a random phage-epitope library. Proc. Natl. Acad. Sci. USA, 90,10643-10647.
2.Luo J and Miller MW (1996). Ethanol inhibits bFGF-mediated proliferation of C6 glioma cells. J. Neurochem., 67, 1448-1456.
3.Torsten G, Hae YS, Gerald AM, and Ulrich P (2002). Shear Stress-induced Release of Basic Fibroblast Growth Factor from Endothelial Cells Is Mediated by Matrix Interaction via Integrin aVß3. J. Biol. Chem., 277, 23453 – 23458.
4.Gloe T, Sohn HY, Gerald AM, and Ulrich P (2002). Shear-stress induced release of bFGF from endothelial cells is mediated by matrix interaction via integrin alpha V beta 3. J. Biol. Chem., 277, 23453.
Bradykinins, Analogs and Sequences
Definition
Bradykinin is a nonapeptide that is mainly found in animal preparations that are treated with the venom of the snake, Bothrops jararaca1,2. It dialates blood vessels that in turn leads to decrease in blood pressure2. Bradykinin analogs are slightly modified structural derivatives of bradykinin that perform similar functions as bradykinin3.
Discovery
Bradykinin was discovered in the blood plasma of animals that were treated with the venom from the Brazilian snake, Bothrops jararaca1,2. The discovery was part of a study that was related to toxicology of snake bites. Bradykinin analogs were synthesized by solid-phase techniques in 1975 and their function was studied in rats and rabbits3.
Classification
Bradykinin is a 9 amino acid peptide that belongs to the kinin family of proteins4. It has homologs in several animals including other snakes, frog, dog and humans4.
Structural Characteristics
Bradykinin has the sequence Arg-Pro-Pro-Gly-Phe-Ser-Pro-Phe-Arg3. Several analogs of bradykinin have been synthesized. They are also nanopeptides containing substitutions of various amino acids of bradykinin. For example two analogs of bradykinin were synthesized one with 7-beta-homo-L-proline and the other with 8-beta-homo-L-phenylalanine substitutions3. It was found that both of them are resistant to enzymatic degradation3.
Mode of action
Bradykinin binds to two different kinin G protein coupled receptors- B1 and B25. Upon binding to these receptors it induces conversion of GTP to GDP which in turn triggers the conversion ATP to cAM which then acts as a second messanger resulting in the activation of genes. B1 receptor is expressed as a result of tissue injury and is found to play a role in inflammation while B2 receptor participates in the vasodilatory role of bradykinin5,6. Bradykinin analogs function is a similar fashion although depending on their structure they might have varying affinities to the receptors compared to bradykinin7. Also analogs of bradykinin have been synthesized that are specific to one of these receptors7.
Functions
Bradykinin is a potent endothelium-dependent vasodilator, causes contraction of non-vascular smooth muscle, increases vascular permeability and also is involved in the mechanism of pain. Bradykinin also causes natriuresis, contributing to a drop in blood pressure8. Bradykinin raises internal calcium levels in neocortical astrocytes causing them to release glutamate9. Overactivation of bradykinin is thought to play a role in a rare disease called Hereditary Angioedema, also known as Hereditary Angio-Neurotic Edema10.
Some analogs of bradykinin have been found to have prolonged hypotensive action compared to bradykinin (Eg: beta-H-Pro-bradykinin)3. Some analogs have relative or even lower potencies compared to bradykinin (Eg: HArg1-Bradykinin and HArg9 Bradykinin)7. Other analogs have been studied for their potential of finding bradykinin antagonists that might be useful in the treatment of angio-neurotic edema.
References
1.Partridge, SM (1948). (Title or abstract not available), Biochem. J., 42, 238.
2.Allen PK, Kusumam J, Yoji S, Yoshitaka N, Berhane G, Sesha R and Michael S (1998). Bradykinin formation: Plasma and tissue pathways and cellular interactions. Clinical reviews in allergy and immunology, 16, 4, 403-429.
3.Ondetti MA, Engel SL (1975). Bradykinin analogs containing beta.-homoamino acid, J. Med. Chem.,18 (7), 761–763.
4.Roseli A, Gomes S, Jair RC, Luis J and Valdemar H (1996). Met-Lys-Bradykinin-Ser, the kinin released from human kininogen by human pepsin. Immunopharmacology, 32, 76-79.
5.Peter GM, Amrita A, and Mauro P (2000). Association between Kinin B1 Receptor Expression and Leukocyte Trafficking across Mouse Mesenteric Postcapillary Venules. J Exp. Med., 192, 367-380.
6.Duchene J, Lecomte F, Ahmed S, Cayla C, Pesquero J, Bader M, Perretti M and Ahluwalia A, (2007). A Novel Inflammatory Pathway Involved in Leukocyte Recruitment: Role for the Kinin B1 Receptor and the Chemokine CXCL5. J Immunol., 179, 4849-4856.
7.Max ES, Phyllis AL (1974). Synthesis and pharmacology of homoarginine bradykinin analog. J. Med. Chem., 17 (11), pp 1227–1228.
8.Dendorfer A, Wolfrum S, Wagemann M, Qadri F, Dominiak P, (2001). Pathways of bradykinin degradation in blood and plasma of normotensive and hypertensive rats. Am J Physiol Heart Circ Physiol., 280:H2182
9.Kuoppala A, Lindstedt KA, Saarinen J, Kovanen PT, Kokkonen JO (2000). Inactivation of bradykinin by angiotensin-converting enzyme and by carboxypeptidase N in human plasma. Am J Physiol Heart Circ Physiol, 278(4):H1069-74.
10.Bas M, Adams V, Suvorava T, Niehues T, Hoffmann TK, Kojda G (2007). Nonallergic angioedema: role of bradykinin. Allergy, 62(8):842-56.
Bradykinin is a nonapeptide that is mainly found in animal preparations that are treated with the venom of the snake, Bothrops jararaca1,2. It dialates blood vessels that in turn leads to decrease in blood pressure2. Bradykinin analogs are slightly modified structural derivatives of bradykinin that perform similar functions as bradykinin3.
Discovery
Bradykinin was discovered in the blood plasma of animals that were treated with the venom from the Brazilian snake, Bothrops jararaca1,2. The discovery was part of a study that was related to toxicology of snake bites. Bradykinin analogs were synthesized by solid-phase techniques in 1975 and their function was studied in rats and rabbits3.
Classification
Bradykinin is a 9 amino acid peptide that belongs to the kinin family of proteins4. It has homologs in several animals including other snakes, frog, dog and humans4.
Structural Characteristics
Bradykinin has the sequence Arg-Pro-Pro-Gly-Phe-Ser-Pro-Phe-Arg3. Several analogs of bradykinin have been synthesized. They are also nanopeptides containing substitutions of various amino acids of bradykinin. For example two analogs of bradykinin were synthesized one with 7-beta-homo-L-proline and the other with 8-beta-homo-L-phenylalanine substitutions3. It was found that both of them are resistant to enzymatic degradation3.
Mode of action
Bradykinin binds to two different kinin G protein coupled receptors- B1 and B25. Upon binding to these receptors it induces conversion of GTP to GDP which in turn triggers the conversion ATP to cAM which then acts as a second messanger resulting in the activation of genes. B1 receptor is expressed as a result of tissue injury and is found to play a role in inflammation while B2 receptor participates in the vasodilatory role of bradykinin5,6. Bradykinin analogs function is a similar fashion although depending on their structure they might have varying affinities to the receptors compared to bradykinin7. Also analogs of bradykinin have been synthesized that are specific to one of these receptors7.
Functions
Bradykinin is a potent endothelium-dependent vasodilator, causes contraction of non-vascular smooth muscle, increases vascular permeability and also is involved in the mechanism of pain. Bradykinin also causes natriuresis, contributing to a drop in blood pressure8. Bradykinin raises internal calcium levels in neocortical astrocytes causing them to release glutamate9. Overactivation of bradykinin is thought to play a role in a rare disease called Hereditary Angioedema, also known as Hereditary Angio-Neurotic Edema10.
Some analogs of bradykinin have been found to have prolonged hypotensive action compared to bradykinin (Eg: beta-H-Pro-bradykinin)3. Some analogs have relative or even lower potencies compared to bradykinin (Eg: HArg1-Bradykinin and HArg9 Bradykinin)7. Other analogs have been studied for their potential of finding bradykinin antagonists that might be useful in the treatment of angio-neurotic edema.
References
1.Partridge, SM (1948). (Title or abstract not available), Biochem. J., 42, 238.
2.Allen PK, Kusumam J, Yoji S, Yoshitaka N, Berhane G, Sesha R and Michael S (1998). Bradykinin formation: Plasma and tissue pathways and cellular interactions. Clinical reviews in allergy and immunology, 16, 4, 403-429.
3.Ondetti MA, Engel SL (1975). Bradykinin analogs containing beta.-homoamino acid, J. Med. Chem.,18 (7), 761–763.
4.Roseli A, Gomes S, Jair RC, Luis J and Valdemar H (1996). Met-Lys-Bradykinin-Ser, the kinin released from human kininogen by human pepsin. Immunopharmacology, 32, 76-79.
5.Peter GM, Amrita A, and Mauro P (2000). Association between Kinin B1 Receptor Expression and Leukocyte Trafficking across Mouse Mesenteric Postcapillary Venules. J Exp. Med., 192, 367-380.
6.Duchene J, Lecomte F, Ahmed S, Cayla C, Pesquero J, Bader M, Perretti M and Ahluwalia A, (2007). A Novel Inflammatory Pathway Involved in Leukocyte Recruitment: Role for the Kinin B1 Receptor and the Chemokine CXCL5. J Immunol., 179, 4849-4856.
7.Max ES, Phyllis AL (1974). Synthesis and pharmacology of homoarginine bradykinin analog. J. Med. Chem., 17 (11), pp 1227–1228.
8.Dendorfer A, Wolfrum S, Wagemann M, Qadri F, Dominiak P, (2001). Pathways of bradykinin degradation in blood and plasma of normotensive and hypertensive rats. Am J Physiol Heart Circ Physiol., 280:H2182
9.Kuoppala A, Lindstedt KA, Saarinen J, Kovanen PT, Kokkonen JO (2000). Inactivation of bradykinin by angiotensin-converting enzyme and by carboxypeptidase N in human plasma. Am J Physiol Heart Circ Physiol, 278(4):H1069-74.
10.Bas M, Adams V, Suvorava T, Niehues T, Hoffmann TK, Kojda G (2007). Nonallergic angioedema: role of bradykinin. Allergy, 62(8):842-56.
Bradykinin-Potentiating Peptides (BPP)
Definition
Bradykinin potentiating peptides (BPPs) isolated from the venom of the snake, Bothrops jararaca increase both the duration and magnitude of bradykinin’s (Nonapeptide found in the blood plasma of animals after injection of venom) effects on vasodilation and the consequent fall in blood pressure1.
Discovery
BPPs were discovered in partially purified preparations of Bothrops jararaca venom by their ability to increase bradykinin activity in vitro in guinea pig ileum and in vivo in rats1.
Classification
BPPs are naturally occurring inhibitors of angiotensin-converting enzyme (ACE) 2. They present a classic motif and can be recognized by their pyroglutamyl rich sequences2.
Structural Characteristics
BPPs are short 5-13 amino acid peptides with a proline rich sequence3. They have a cyclised form of glutamic acid as their N-terminus. For example, the structure of an active BPP pentapeptide is pyrrolidone-carboxyl-Lys-Trp-Ala-Pro3.
Mode of action
BPPs potentiate bradykinin activity primarily by blocking the function of kininase enzymes which are inhibitors of bradykinin4. They are also known to increase bradykinin’s affinity to its receptors by promoting their sensitization4.
Functions
The chemical and pharmacological properties of BPPs were used for the development of captopril, the first active site directed inhibitor of ACE, currently used to treat human hypertension5. BPPs increase bradykinin activity in non-vascular smooth muscle contraction, vasodilation and lowering of blood pressure6.
References
1. Ferreira, SH (1965). Bradykinin-potentiating factor (BPF) present in venom of Bothropsjararaca. Br. J. Pharmac. Chemother., 24, 163-169.
2.Katia C, Katsuhiro K, Robson Lopes DM, Marta MA, Carlos J, Juliana MS, Isaltino MC, Benedito CP, Antônio CMDC and Daniel CP (2006). Isolation and characterization of a novel bradykinin potentiating peptide (BPP) from the skin secretion of Phyllomedusa hypochondrialis. Peptides, 28, 3, 515-523.
3.Lewis JG, Sergio HF and John MS (1971). Bradykinin Potentiating Factor. Chest, 59;9S-10S.
4.Camargo A and Ferreira SH (1971). Action of bradykinin potentiating factor (BPF) and dimercaprol (BAL) on the responses to bradykinin of isolated preparations of rat intestines. Br J Pharmacol., 42(2): 305–307.
5.Fernandez JH, Neshich G and Camargo ACM (2004). Using bradykinin-potentiating peptide structures to develop new antihypertensive drugs. Genet. Mol. Res., 3 (4): 554-563.
6.Mueller S, Gothe R, Siems WD, Vietinghoff G, Paegelow I, Reissmann S (2005). Potentiation of bradykinin actions by analogues of the bradykinin potentiating nonapeptide BPP9 alpha. Peptides, 26(7):1235-47.
Bradykinin potentiating peptides (BPPs) isolated from the venom of the snake, Bothrops jararaca increase both the duration and magnitude of bradykinin’s (Nonapeptide found in the blood plasma of animals after injection of venom) effects on vasodilation and the consequent fall in blood pressure1.
Discovery
BPPs were discovered in partially purified preparations of Bothrops jararaca venom by their ability to increase bradykinin activity in vitro in guinea pig ileum and in vivo in rats1.
Classification
BPPs are naturally occurring inhibitors of angiotensin-converting enzyme (ACE) 2. They present a classic motif and can be recognized by their pyroglutamyl rich sequences2.
Structural Characteristics
BPPs are short 5-13 amino acid peptides with a proline rich sequence3. They have a cyclised form of glutamic acid as their N-terminus. For example, the structure of an active BPP pentapeptide is pyrrolidone-carboxyl-Lys-Trp-Ala-Pro3.
Mode of action
BPPs potentiate bradykinin activity primarily by blocking the function of kininase enzymes which are inhibitors of bradykinin4. They are also known to increase bradykinin’s affinity to its receptors by promoting their sensitization4.
Functions
The chemical and pharmacological properties of BPPs were used for the development of captopril, the first active site directed inhibitor of ACE, currently used to treat human hypertension5. BPPs increase bradykinin activity in non-vascular smooth muscle contraction, vasodilation and lowering of blood pressure6.
References
1. Ferreira, SH (1965). Bradykinin-potentiating factor (BPF) present in venom of Bothropsjararaca. Br. J. Pharmac. Chemother., 24, 163-169.
2.Katia C, Katsuhiro K, Robson Lopes DM, Marta MA, Carlos J, Juliana MS, Isaltino MC, Benedito CP, Antônio CMDC and Daniel CP (2006). Isolation and characterization of a novel bradykinin potentiating peptide (BPP) from the skin secretion of Phyllomedusa hypochondrialis. Peptides, 28, 3, 515-523.
3.Lewis JG, Sergio HF and John MS (1971). Bradykinin Potentiating Factor. Chest, 59;9S-10S.
4.Camargo A and Ferreira SH (1971). Action of bradykinin potentiating factor (BPF) and dimercaprol (BAL) on the responses to bradykinin of isolated preparations of rat intestines. Br J Pharmacol., 42(2): 305–307.
5.Fernandez JH, Neshich G and Camargo ACM (2004). Using bradykinin-potentiating peptide structures to develop new antihypertensive drugs. Genet. Mol. Res., 3 (4): 554-563.
6.Mueller S, Gothe R, Siems WD, Vietinghoff G, Paegelow I, Reissmann S (2005). Potentiation of bradykinin actions by analogues of the bradykinin potentiating nonapeptide BPP9 alpha. Peptides, 26(7):1235-47.
Wednesday, June 17, 2009
Bacterial Peptides
Definition
Bacterial peptides are protein fragments which are either part of a bacterium or produced by a bacteria1.
Classification
Different classes of peptides are produced by bacteria. Some examples include, antibiotics, enterotoxins, flagellar proteins, lipoproteins and various enzymes1.
Structural Characteristics
Structural characteristics of some bacterial peptides are described below-
A)Malaria merozoite surface peptide (MSP-1): It is synthesized as a large precursor on the surface of the bacterium Plasmodium falciparum. Proteolytic cleavage results in the production of a 19 KDa product whose tertiary structure is maintained by disulphide bridges2.
B)Giardia variable surface protein: This peptide is the specific conserved region of the Giardia variable surface proteins (VSPs) that are cysteine rich zinc finger proteins. VSPs differ in size and sequence, they are characterized by this highly conserved C-terminal membrane spanning region, a hydrophilic cytoplasmic tail with a conserved five amino acid CRGKA signature sequence3,4.
C)P.falciparum liver stage antigen 3: The protein is 200Kda and is highly conserved among parasites from different geographic regions5.
Mode of action
A)MSP-1 is known to trigger antibody response by CD4 helper T cells. It is likely that these cells bind to the C-terminal domain of MSP-12.
B)VSPs have a conserved hydrophilic amono acid trail that is palmitoyted by palmityl tranferases upon which they are activated3,4.
C)P. falciparum liver stage antigen 3 is a potent antigen that is recongnized by T cells5.
Functions
A)MSP-1 is a vaccine candidate for Plasmodium falciparum infection. It triggers a CD-4 T cell response2.
B)VSPs are necessary for survival in the environment and host infection3,4.
C)P.falciparum stage antigen 3 is also a good candidate vaccine as it activates both T and B cell responses5.
Bacterial peptides are protein fragments which are either part of a bacterium or produced by a bacteria1.
Classification
Different classes of peptides are produced by bacteria. Some examples include, antibiotics, enterotoxins, flagellar proteins, lipoproteins and various enzymes1.
Structural Characteristics
Structural characteristics of some bacterial peptides are described below-
A)Malaria merozoite surface peptide (MSP-1): It is synthesized as a large precursor on the surface of the bacterium Plasmodium falciparum. Proteolytic cleavage results in the production of a 19 KDa product whose tertiary structure is maintained by disulphide bridges2.
B)Giardia variable surface protein: This peptide is the specific conserved region of the Giardia variable surface proteins (VSPs) that are cysteine rich zinc finger proteins. VSPs differ in size and sequence, they are characterized by this highly conserved C-terminal membrane spanning region, a hydrophilic cytoplasmic tail with a conserved five amino acid CRGKA signature sequence3,4.
C)P.falciparum liver stage antigen 3: The protein is 200Kda and is highly conserved among parasites from different geographic regions5.
Mode of action
A)MSP-1 is known to trigger antibody response by CD4 helper T cells. It is likely that these cells bind to the C-terminal domain of MSP-12.
B)VSPs have a conserved hydrophilic amono acid trail that is palmitoyted by palmityl tranferases upon which they are activated3,4.
C)P. falciparum liver stage antigen 3 is a potent antigen that is recongnized by T cells5.
Functions
A)MSP-1 is a vaccine candidate for Plasmodium falciparum infection. It triggers a CD-4 T cell response2.
B)VSPs are necessary for survival in the environment and host infection3,4.
C)P.falciparum stage antigen 3 is also a good candidate vaccine as it activates both T and B cell responses5.
Protein post-translational modifications
Post-translational modifications are the chemical modifications of proteins subsequent to their biosynthesis. The modification of certain amino acid residues may result in changes of the protein conformation and/or its capacity to interact with other proteins or ligands, to be active or inactive in the case of an enzyme, to allow or interfere with gene expression and many other biological functions. These modifications have been found by using radioactively labeled compounds, to yield a protein(s) carrying a radioactive tag located in the modifying group and that can be detected by methods such as autoradiography, liquid scintillation, and other methods after resolution of the different compounds by electrophoresis, chromatography and other separation procedures.
Confirmation of the modification is carried out by chemical synthesis of the modified amino acid and its structural confirmation by mass spectra. Once the nature of the modification has been establish, the most straightforward method of detecting it is by the use of specific antibodies against the chemical modification. Use of tagged antibodies would allow to detect the distribution of the modification in tissues by using histochemical methods and its evaluation by immune assays such as ELISA.
Although there are many post-translational modifications, some have shown to be crucial for several biological functions, such as:
·Phosphorylation or the addition of a phosphate group to tyrosine, serine, threonine or histidine. This modification affects the activity of certain oncoproteins, eg. Her and EGF.
·Acylation or the addition of an acetyl group to the lysine residues of a protein and/or its terminal amino group. This modification happens usually in histones and regulates the expression of certain genes in a mechanism know as epigenetic effects.
·Prenylation is the addition of a prenyl groups that are hydrophobic to the C-terminal cysteine residues of a protein. It occurs in several oncoprotein and the most common prenyl groups are farnesyl and geranyl-geranyl groups.
·Glycation is the addition of reducing sugar to a lysine amino group via a Schiff base. This modification plays an important role in diabetes.
·ADP-ribosylation is a modification in which ADP-ribose moieties are incorporated the arginine, glutamic or aspartic acid residues of a protein. This modification is involved in signaling and control processes such as DNA repair and apoptosis.
·Post-translational modifications also involve conjugation of a protein to other proteins or peptides, such as ubiquitylation or linkage to the protein ubiquitin. This modification tags an obsolete protein for degradation by the proteosomes.
Other modifications include the formation and cleavage of disulfide bonds, deamination of glutamine, asparagine and arginine. Modifications that contribute to changes in the structural properties of a protein.
An important post-translational modification is the proteolytic cleavage of the lipophilic amino acid sequence in some protein precursors, which is needed to translocate the protein across the lipid bilayer of cellular membranes.
Glycosylation of proteins to yield glycoproteins is a modification that plays an important role in the movement and recognition of cells from the immune system. Glycosylation also have a role in differentiation as well as cancer metastasis. Addition of the sugar residues, take place at the asparagine, serine ot threonine amino acids.
In addition, there are some post-translational modifications that are introduce into purified proteins, such as pegylation, to limit the immunogenicity of a protein. Free amino groups from proteins can be converted to carboxylic grops by succinylation, a modification that changes a cationic protein to an anionic one.
As mentioned before, the use of specific antibodies to these modifications is the easiest way to detect and follow them. BioSynthesis monospecific antibodies are prepared using our own modified antigens and using proprietary immunostimulants to obtain high affinity antibodies. These antibodies can be supply as antisera or as purified antibodies and their conjugates with fluorescent tags and enzymes.
Confirmation of the modification is carried out by chemical synthesis of the modified amino acid and its structural confirmation by mass spectra. Once the nature of the modification has been establish, the most straightforward method of detecting it is by the use of specific antibodies against the chemical modification. Use of tagged antibodies would allow to detect the distribution of the modification in tissues by using histochemical methods and its evaluation by immune assays such as ELISA.
Although there are many post-translational modifications, some have shown to be crucial for several biological functions, such as:
·Phosphorylation or the addition of a phosphate group to tyrosine, serine, threonine or histidine. This modification affects the activity of certain oncoproteins, eg. Her and EGF.
·Acylation or the addition of an acetyl group to the lysine residues of a protein and/or its terminal amino group. This modification happens usually in histones and regulates the expression of certain genes in a mechanism know as epigenetic effects.
·Prenylation is the addition of a prenyl groups that are hydrophobic to the C-terminal cysteine residues of a protein. It occurs in several oncoprotein and the most common prenyl groups are farnesyl and geranyl-geranyl groups.
·Glycation is the addition of reducing sugar to a lysine amino group via a Schiff base. This modification plays an important role in diabetes.
·ADP-ribosylation is a modification in which ADP-ribose moieties are incorporated the arginine, glutamic or aspartic acid residues of a protein. This modification is involved in signaling and control processes such as DNA repair and apoptosis.
·Post-translational modifications also involve conjugation of a protein to other proteins or peptides, such as ubiquitylation or linkage to the protein ubiquitin. This modification tags an obsolete protein for degradation by the proteosomes.
Other modifications include the formation and cleavage of disulfide bonds, deamination of glutamine, asparagine and arginine. Modifications that contribute to changes in the structural properties of a protein.
An important post-translational modification is the proteolytic cleavage of the lipophilic amino acid sequence in some protein precursors, which is needed to translocate the protein across the lipid bilayer of cellular membranes.
Glycosylation of proteins to yield glycoproteins is a modification that plays an important role in the movement and recognition of cells from the immune system. Glycosylation also have a role in differentiation as well as cancer metastasis. Addition of the sugar residues, take place at the asparagine, serine ot threonine amino acids.
In addition, there are some post-translational modifications that are introduce into purified proteins, such as pegylation, to limit the immunogenicity of a protein. Free amino groups from proteins can be converted to carboxylic grops by succinylation, a modification that changes a cationic protein to an anionic one.
As mentioned before, the use of specific antibodies to these modifications is the easiest way to detect and follow them. BioSynthesis monospecific antibodies are prepared using our own modified antigens and using proprietary immunostimulants to obtain high affinity antibodies. These antibodies can be supply as antisera or as purified antibodies and their conjugates with fluorescent tags and enzymes.
ATPase
Definition
ATPases are a class of enzymes that catalyze the decomposition of adenosine triphosphate (ATP) into adenosine diphosphate (ADP) and a free phosphate ion.
Discovery
Na+/K+-ATPase was discovered by Danish biologist Jens Christian Skou in 19571.
Classification
There are different types of ATPases which differs in their functions, structure and in the type of ions they transport viz., F-ATPases, V-ATPases, A-ATPases, P-ATPases and E-ATPases. F-ATPases are found in mitochondria, chloroplasts and bacterial plasma membranes produce ATP, using the proton gradient generated by oxidative phosphorylation (mitochondria) or photosynthesis (chloroplasts). V-ATPases are found in eukaryotic vacuoles, catalyzing ATP hydrolysis to transport solutes and lower pH in organelles. A-ATPases are found in Archaea and their functionality is similar to F-ATPases. P-ATPases are found in bacteria, fungi and in eukaryotic plasma membranes and organelles, and function to transport a variety of different ions across membranes. E-ATPases are cell-surface enzymes that hydrolyse a range of NTPs, viz., extracellular ATP.
Structural characteristics
ATPases are integral membrane proteins and move solutes across the membrane. Na+-K+-ATPase is composed of two subunits. The alpha subunit (~113 kDa) binds ATP and both sodium and potassium ions, and contains the phosphorylation site. The smaller beta subunit (~35 kDa glycoprotein) is necessary for activity of the complex. It appears to be critical in facilitating the plasma membrane localization and activation of the alpha subunit2.
Mode of action
The sodium-potassium exchanger (Na+/K+ATPase) enzymatic activity is initiated by binding to ATP and three intracellular Na+ ions. ATP is hydrolyzed, leading to phosphorylation of a cytoplasmic loop of the pump and release of ADP. A conformational change in the pump exposes the Na+ ions to the outside, where they are released. The pump binds two extracellular K+ ions, leading to dephosphorylation of the alpha subunit. ATP binds and the pump reorients to release K+ ions inside the cell, which results in electrical gradient across the cell membrane.
Functions
ATPases import many of the metabolites like glucose, amino acids and other nutrients into the cell necessary for cell metabolism and export toxins, wastes, and other solutes that can hinder cellular processes. The ionic transport conducted by sodium pumps (Na+/K+ATPase) creates both an electrical and chemical gradient across the plasma membrane. It helps in electrolyte movement across epithelial cells. The cell's resting membrane potential is a manifestation of the electrical gradient, and the gradient is the basis for excitability in nerve and muscle cells. The hydrogen potassium ATPase (H+/K+ATPase or gastric proton pump) acidifies the contents in the stomach3.
References
1.Boldyrev AA (2000). Na+,K+-ATPase: 40 years of investigations. Membr Cell Biol., 13(6):715-719.
2.Lingrel JB, Kuntzweiler T (1994). Na+, K+-ATPase. J Biol Chem., 269:19659.
3.Schubert, Mitchell L (2007). Gastric secretion. Current Opinion in Gastroenterology., 23(6) 595-601.
ATPases are a class of enzymes that catalyze the decomposition of adenosine triphosphate (ATP) into adenosine diphosphate (ADP) and a free phosphate ion.
Discovery
Na+/K+-ATPase was discovered by Danish biologist Jens Christian Skou in 19571.
Classification
There are different types of ATPases which differs in their functions, structure and in the type of ions they transport viz., F-ATPases, V-ATPases, A-ATPases, P-ATPases and E-ATPases. F-ATPases are found in mitochondria, chloroplasts and bacterial plasma membranes produce ATP, using the proton gradient generated by oxidative phosphorylation (mitochondria) or photosynthesis (chloroplasts). V-ATPases are found in eukaryotic vacuoles, catalyzing ATP hydrolysis to transport solutes and lower pH in organelles. A-ATPases are found in Archaea and their functionality is similar to F-ATPases. P-ATPases are found in bacteria, fungi and in eukaryotic plasma membranes and organelles, and function to transport a variety of different ions across membranes. E-ATPases are cell-surface enzymes that hydrolyse a range of NTPs, viz., extracellular ATP.
Structural characteristics
ATPases are integral membrane proteins and move solutes across the membrane. Na+-K+-ATPase is composed of two subunits. The alpha subunit (~113 kDa) binds ATP and both sodium and potassium ions, and contains the phosphorylation site. The smaller beta subunit (~35 kDa glycoprotein) is necessary for activity of the complex. It appears to be critical in facilitating the plasma membrane localization and activation of the alpha subunit2.
Mode of action
The sodium-potassium exchanger (Na+/K+ATPase) enzymatic activity is initiated by binding to ATP and three intracellular Na+ ions. ATP is hydrolyzed, leading to phosphorylation of a cytoplasmic loop of the pump and release of ADP. A conformational change in the pump exposes the Na+ ions to the outside, where they are released. The pump binds two extracellular K+ ions, leading to dephosphorylation of the alpha subunit. ATP binds and the pump reorients to release K+ ions inside the cell, which results in electrical gradient across the cell membrane.
Functions
ATPases import many of the metabolites like glucose, amino acids and other nutrients into the cell necessary for cell metabolism and export toxins, wastes, and other solutes that can hinder cellular processes. The ionic transport conducted by sodium pumps (Na+/K+ATPase) creates both an electrical and chemical gradient across the plasma membrane. It helps in electrolyte movement across epithelial cells. The cell's resting membrane potential is a manifestation of the electrical gradient, and the gradient is the basis for excitability in nerve and muscle cells. The hydrogen potassium ATPase (H+/K+ATPase or gastric proton pump) acidifies the contents in the stomach3.
References
1.Boldyrev AA (2000). Na+,K+-ATPase: 40 years of investigations. Membr Cell Biol., 13(6):715-719.
2.Lingrel JB, Kuntzweiler T (1994). Na+, K+-ATPase. J Biol Chem., 269:19659.
3.Schubert, Mitchell L (2007). Gastric secretion. Current Opinion in Gastroenterology., 23(6) 595-601.
Annexin
Definition
Annexins are calcium-dependent phospholipid-binding proteins. More than a thousand proteins of the annexin superfamily have been identified in major eukaryotic phyla, but annexins are absent from yeasts and prokaryotes.
Discovery
The first annexin to be identified was annexin VII (synexin) from the bovine adrenal medulla by creutz and team in 19781.
Classification
Annexins are grouped under 5 major classes (A-E), the 12 annexins which are commonly found in vertebrates are classified under annexin A family and named as annexins A1-A13 (or ANXA1-ANXA13), leaving A12 not assigned in the official nomenclature. Annexins outside vertebrates are classified under family B (in invertebrates), C (in fungi and under groups of unicellular eukaryotes), D (in plants), and E (in protists).
Structural Characteristics
Each annexin is composed of two principal domains: the divergent NH2-terminal “head” and the conserved COOH-terminal protein core. The COOH-terminal protein core harbors the Ca2+ and membrane binding sites and is responsible for mediating the canonical membrane binding properties. An annexin core comprises four (in annexin A6 eight) segments of internal and interannexin homology that are easily identified in a linear sequence alignment. It forms a highly alpha helical and tightly packed disk with a slight curvature and two principle sides. The more convex side contains Ca2+ binding sites, the so-called type II and type III sites, and faces the membrane when an annexin is associated peripherally with phospholipids2. Many annexins undergo posttranslational modifications viz., phosphorylation and myristoylation1.
Mode of action
The process of membrane aggreagation requires the self association of annexin molecules where Ca2+ plays an important role. In case of synexin (annexin VII) at lower concentration of Ca2+ level it is soluble, if the concentration of Ca2+ increase it results in binding of annexins to membrane further increase in Ca2+ levels results in membrane aggregation and fusion.
Function
Annexins interact with various cell-membrane components that are involved in the structural organization of the cell, intracellular signaling by enzyme modulation and ion fluxes, growth control, and they can act as atypical calcium channels1.
References
1.Moss SE, Morgan RO (2004). The Annexins. Genome Biol., 5(4): 219.
Annexins are calcium-dependent phospholipid-binding proteins. More than a thousand proteins of the annexin superfamily have been identified in major eukaryotic phyla, but annexins are absent from yeasts and prokaryotes.
Discovery
The first annexin to be identified was annexin VII (synexin) from the bovine adrenal medulla by creutz and team in 19781.
Classification
Annexins are grouped under 5 major classes (A-E), the 12 annexins which are commonly found in vertebrates are classified under annexin A family and named as annexins A1-A13 (or ANXA1-ANXA13), leaving A12 not assigned in the official nomenclature. Annexins outside vertebrates are classified under family B (in invertebrates), C (in fungi and under groups of unicellular eukaryotes), D (in plants), and E (in protists).
Structural Characteristics
Each annexin is composed of two principal domains: the divergent NH2-terminal “head” and the conserved COOH-terminal protein core. The COOH-terminal protein core harbors the Ca2+ and membrane binding sites and is responsible for mediating the canonical membrane binding properties. An annexin core comprises four (in annexin A6 eight) segments of internal and interannexin homology that are easily identified in a linear sequence alignment. It forms a highly alpha helical and tightly packed disk with a slight curvature and two principle sides. The more convex side contains Ca2+ binding sites, the so-called type II and type III sites, and faces the membrane when an annexin is associated peripherally with phospholipids2. Many annexins undergo posttranslational modifications viz., phosphorylation and myristoylation1.
Mode of action
The process of membrane aggreagation requires the self association of annexin molecules where Ca2+ plays an important role. In case of synexin (annexin VII) at lower concentration of Ca2+ level it is soluble, if the concentration of Ca2+ increase it results in binding of annexins to membrane further increase in Ca2+ levels results in membrane aggregation and fusion.
Function
Annexins interact with various cell-membrane components that are involved in the structural organization of the cell, intracellular signaling by enzyme modulation and ion fluxes, growth control, and they can act as atypical calcium channels1.
References
1.Moss SE, Morgan RO (2004). The Annexins. Genome Biol., 5(4): 219.
Calcineurin (PP2B)
Definition
Calcineurin also known as protein phosphatase 2B (PP2B), is a phosphoprotein serine/threonine phosphatase, activated physiologically by Ca2+–calmodulin.
Discovery
It was identified and characterized by Claude Klee and Philip Cohen in the late 1970s.
Structural Characteristics
Calcineurin is a dimer of an A catalytic subunit and a B subunit. Calmodulin becomes tightly associated with calcineurin only in the presence of elevated, but physiological, levels of Ca2+ 1.
Classification
In mammals three isoforms of calcineurin A (Aa, Aß and A?) and two isoforms of calcineurin B (B1, and B2) are expressed from separate genes1.
Mode of action
In resting cells, nuclear factor of activated T-cells (NFAT) proteins are phosphorylated, and in cells exposed to stimuli that raise intracellular free Ca2+ levels, they are dephosphorylated by the calmodulin-dependent phosphatase calcineurin. On dephosphorylation NFAT translocate to the nucleus whereon, it binds to consensus DNA sites and controls gene transcription2.
Functions
Calcineurin plan an important role in intracellular signaling. In budding yeast, calcineurin has a role in coordinating adaptation to environmental stress both through the calcineurin–Crz1p transcriptional pathway and through post-translational mechanisms. Calcineurin signaling is involved in the long-term adaptation after chronic drug treatment in a way that may parallel its role during memory formation3.
References
1.Hogan PG, Li H (2005). Calcineurin. Curr Biol., 15(12):442-443.
2.Valerie Horsley and Grace K. Pavlath (2002). Nfat: ubiquitous regulator of cell differentiation and adaptation. J Cell Biol., 156(5): 771–774.
3.Biala G (2007). Memory processes and addiction: involvement of the calcineurin signaling pathway. Postepy Hig Med Dosw (Online)., 61:199-203.
Calcineurin also known as protein phosphatase 2B (PP2B), is a phosphoprotein serine/threonine phosphatase, activated physiologically by Ca2+–calmodulin.
Discovery
It was identified and characterized by Claude Klee and Philip Cohen in the late 1970s.
Structural Characteristics
Calcineurin is a dimer of an A catalytic subunit and a B subunit. Calmodulin becomes tightly associated with calcineurin only in the presence of elevated, but physiological, levels of Ca2+ 1.
Classification
In mammals three isoforms of calcineurin A (Aa, Aß and A?) and two isoforms of calcineurin B (B1, and B2) are expressed from separate genes1.
Mode of action
In resting cells, nuclear factor of activated T-cells (NFAT) proteins are phosphorylated, and in cells exposed to stimuli that raise intracellular free Ca2+ levels, they are dephosphorylated by the calmodulin-dependent phosphatase calcineurin. On dephosphorylation NFAT translocate to the nucleus whereon, it binds to consensus DNA sites and controls gene transcription2.
Functions
Calcineurin plan an important role in intracellular signaling. In budding yeast, calcineurin has a role in coordinating adaptation to environmental stress both through the calcineurin–Crz1p transcriptional pathway and through post-translational mechanisms. Calcineurin signaling is involved in the long-term adaptation after chronic drug treatment in a way that may parallel its role during memory formation3.
References
1.Hogan PG, Li H (2005). Calcineurin. Curr Biol., 15(12):442-443.
2.Valerie Horsley and Grace K. Pavlath (2002). Nfat: ubiquitous regulator of cell differentiation and adaptation. J Cell Biol., 156(5): 771–774.
3.Biala G (2007). Memory processes and addiction: involvement of the calcineurin signaling pathway. Postepy Hig Med Dosw (Online)., 61:199-203.
Bombesin and Analogs
Definition
Bombesin is a polypeptide that is found in the brain and gastrointestinal tract. Experimentally it has shown to cause the secretion of various substances (as gastrin and cholecystokinin) and to inhibit intestinal motility.
Discovery
Bombesin was isolated from the skin of the frog Bombina bonmina by Anastasi and team in 19711.
Classification
Bombesin-like peptides are grouped into three families - 1) Bombesin group, viz., bombesin and alytesin, 2) Ranatensin group viz., ranatensins, litorin, and Rohdei litorin, 3) Phyllolitorin group viz., Leu(8)- and Phe(8)-phyllolitorins.
Structural characteristics
Bombesin is a small peptide of 14 amino acids.
Mode of action
The biological activity of bombesin is mediated by binding to specific receptors viz., gastrin releasing peptide receptor (GRPR; called also BB2 receptor), neuromedin B receptor (NMBR; called also BB1 receptor) and bombesin receptor subtype 3 (BRS-3; called also BB3 receptor). Bombesin induce Ca2+ release from intracellular stores2.
Functions
Bombesin and bombesin-like factors show a wide spectrum of biological activities. It regulates the contraction of smooth muscle cells, induction of the secretion of neuropeptides and hormones. It is one of the most powerful substances showing anorexic effects in the hypothalamus. It induces the release of gastrin and cholecystokinin in the intestines and the pancreas. They also posses activities of cytokines.
References
1.Anastasi A, Erspamer V, Bucci M (1971). Isolation and structure of bombesin and alytesin, 2 analogous active peptides from the skin of the European amphibians Bombina and Alytes. Experientia., 27(2):166-167.
2. Wang JL, Kalyanaraman S, Vivo MD, Gautam N (1996). Bombesin and thrombin affect discrete pools of intracellular calcium through different G-proteins. Biochem J., 320:87-91.
Bombesin is a polypeptide that is found in the brain and gastrointestinal tract. Experimentally it has shown to cause the secretion of various substances (as gastrin and cholecystokinin) and to inhibit intestinal motility.
Discovery
Bombesin was isolated from the skin of the frog Bombina bonmina by Anastasi and team in 19711.
Classification
Bombesin-like peptides are grouped into three families - 1) Bombesin group, viz., bombesin and alytesin, 2) Ranatensin group viz., ranatensins, litorin, and Rohdei litorin, 3) Phyllolitorin group viz., Leu(8)- and Phe(8)-phyllolitorins.
Structural characteristics
Bombesin is a small peptide of 14 amino acids.
Mode of action
The biological activity of bombesin is mediated by binding to specific receptors viz., gastrin releasing peptide receptor (GRPR; called also BB2 receptor), neuromedin B receptor (NMBR; called also BB1 receptor) and bombesin receptor subtype 3 (BRS-3; called also BB3 receptor). Bombesin induce Ca2+ release from intracellular stores2.
Functions
Bombesin and bombesin-like factors show a wide spectrum of biological activities. It regulates the contraction of smooth muscle cells, induction of the secretion of neuropeptides and hormones. It is one of the most powerful substances showing anorexic effects in the hypothalamus. It induces the release of gastrin and cholecystokinin in the intestines and the pancreas. They also posses activities of cytokines.
References
1.Anastasi A, Erspamer V, Bucci M (1971). Isolation and structure of bombesin and alytesin, 2 analogous active peptides from the skin of the European amphibians Bombina and Alytes. Experientia., 27(2):166-167.
2. Wang JL, Kalyanaraman S, Vivo MD, Gautam N (1996). Bombesin and thrombin affect discrete pools of intracellular calcium through different G-proteins. Biochem J., 320:87-91.
Tuesday, June 16, 2009
BAD Peptides
Definition
BAD is a member of the BCl-2 family of proteins and acts to promote apoptosis by forming heterodimers with the survival proteins BCL-2 and BCLXL, thus preventing them from binding with BAX1.
Discovery
BAD was originally identified in a yeast two hybrid system that was used to screen for BCL-2 interacting proteins1.
Classification
BAD belongs to the BH3 sub-family of proteins that also includes other pro-apoptotic proteins; BH3 BID, BIK, BLK, HRK, BNIP3 and BIML2.
Structural Characteristics
BAD peptides contain a highly conserved alpha-helical BH3 domain through which they form heterodimers with BCL-2 and BCLXL3. The BH3 domain is structurally defined as four-turn amphipathic a-helices, containing the sequence motif: Hy-X-X-X-Hy-X-X-X-Sm-D/E-X-Hy4. This domain is sufficient for pro-apoptotic functions of BAD.
Mode of action
BAD peptides are located on the outer-mitochondrail membrane. Activation of NGF or IL-3 receptors on the mitochondrial membrane mediates the activation of AKT or PKA holoenzyme respectively that result in the phosphorylation of BAD at Ser-136 and 1122,5. Phosphorylated BAD is translocated to the cytosol by phosphoserine binding protein. Following a death signal BAD is dephosporylated and found in association with BCL-XL-BCL-2 in which form BAD can exert its functions6.
Functions
BCL-2 family proteins that includes BAD play a pivotal role in deciding whether a cell will live or die by apoptosis. Pro-apoptotic function of BAD is triggered by growth factor deprivation in the cell that results in its dephosphorylation and activation7. Activated BAD binds to BCL-2-BCL-XL and releases BAK and BAX that initiate apoptosis. Increased BAD protein levels have been found in diseases like myocardial ischemia-reperfusion7. BAD is also implicated in cancer. In mouse models it has been found that decrease in BAD levels leads to malignancy8. Interestingly recent studies have shown that the tumor suppressor protein, p53 binds to BAD in response to DNA damage and in turn BAD triggers apoptosis of such cells thus maintaining cell physiology9.
References
1. Elizabeth Y, Jiping Z, Jennifer J, Boise LH, Craig B, Thompson and Stanley JK, (1995). Bad, a heterodimeric partner for Bcl-xL and Bcl-2, displaces bax and promotes cell death. Cell, 80, Issue 2, 285-91.
2. Atan G, James M.M, Stanley J.K (1999). BCL-2 family members and the mitochondria in apoptosis. Genes and Development, 13; 1899-1911.
3. Sabine O, Jose-L D, William H, Julia C, Yan W, Gary W, Steve C, Suzanne W, Lawrence CF, and Tilman O (1997). Structural properties of Human BAD. J Biol. Chem., 372, 49, 30866-892.
4. Beth L, Sangita S and Guido K (2008). Bcl-2 family members; Dual regulators of apoptosis and autophagy. Autophagy, 4:5, 600-606.
5. Zha J, Harada H, Yang E, Jockel J, Kormeyer SJ (1996c). Serine phosphorylation of death agonist BAD in response to survival factor results in binding to 14-3-3 not BCL-X(L). Cell, 87:619–628.
6. Zha J, Harada H, Osipov K, Jockel J, Waksman G, Korsmeyer SJ (1997). BH3 domain of BAD is required for heterodimerization with BCL-XL and pro-apoptotic activity. J. Biol. Chem., 272:24101–24104.
7. Åsa BG and Roberta AG (2007). Bcl-2 family members and apoptosis, taken to heart. Am J Physiol Cell Physiol., 292:45-51.
8. Zinkel S, Gross A and Yang E (2006). BCL2 family in DNA damage and cell cycle control. Cell Death and Differentiation, 13, 1351–1359.
9. Peng J, Wenjing D and Mian W (2007). p53 and BAD: Remote strangers become close friends, Cell Research, 17: 283–285.
BAD is a member of the BCl-2 family of proteins and acts to promote apoptosis by forming heterodimers with the survival proteins BCL-2 and BCLXL, thus preventing them from binding with BAX1.
Discovery
BAD was originally identified in a yeast two hybrid system that was used to screen for BCL-2 interacting proteins1.
Classification
BAD belongs to the BH3 sub-family of proteins that also includes other pro-apoptotic proteins; BH3 BID, BIK, BLK, HRK, BNIP3 and BIML2.
Structural Characteristics
BAD peptides contain a highly conserved alpha-helical BH3 domain through which they form heterodimers with BCL-2 and BCLXL3. The BH3 domain is structurally defined as four-turn amphipathic a-helices, containing the sequence motif: Hy-X-X-X-Hy-X-X-X-Sm-D/E-X-Hy4. This domain is sufficient for pro-apoptotic functions of BAD.
Mode of action
BAD peptides are located on the outer-mitochondrail membrane. Activation of NGF or IL-3 receptors on the mitochondrial membrane mediates the activation of AKT or PKA holoenzyme respectively that result in the phosphorylation of BAD at Ser-136 and 1122,5. Phosphorylated BAD is translocated to the cytosol by phosphoserine binding protein. Following a death signal BAD is dephosporylated and found in association with BCL-XL-BCL-2 in which form BAD can exert its functions6.
Functions
BCL-2 family proteins that includes BAD play a pivotal role in deciding whether a cell will live or die by apoptosis. Pro-apoptotic function of BAD is triggered by growth factor deprivation in the cell that results in its dephosphorylation and activation7. Activated BAD binds to BCL-2-BCL-XL and releases BAK and BAX that initiate apoptosis. Increased BAD protein levels have been found in diseases like myocardial ischemia-reperfusion7. BAD is also implicated in cancer. In mouse models it has been found that decrease in BAD levels leads to malignancy8. Interestingly recent studies have shown that the tumor suppressor protein, p53 binds to BAD in response to DNA damage and in turn BAD triggers apoptosis of such cells thus maintaining cell physiology9.
References
1. Elizabeth Y, Jiping Z, Jennifer J, Boise LH, Craig B, Thompson and Stanley JK, (1995). Bad, a heterodimeric partner for Bcl-xL and Bcl-2, displaces bax and promotes cell death. Cell, 80, Issue 2, 285-91.
2. Atan G, James M.M, Stanley J.K (1999). BCL-2 family members and the mitochondria in apoptosis. Genes and Development, 13; 1899-1911.
3. Sabine O, Jose-L D, William H, Julia C, Yan W, Gary W, Steve C, Suzanne W, Lawrence CF, and Tilman O (1997). Structural properties of Human BAD. J Biol. Chem., 372, 49, 30866-892.
4. Beth L, Sangita S and Guido K (2008). Bcl-2 family members; Dual regulators of apoptosis and autophagy. Autophagy, 4:5, 600-606.
5. Zha J, Harada H, Yang E, Jockel J, Kormeyer SJ (1996c). Serine phosphorylation of death agonist BAD in response to survival factor results in binding to 14-3-3 not BCL-X(L). Cell, 87:619–628.
6. Zha J, Harada H, Osipov K, Jockel J, Waksman G, Korsmeyer SJ (1997). BH3 domain of BAD is required for heterodimerization with BCL-XL and pro-apoptotic activity. J. Biol. Chem., 272:24101–24104.
7. Åsa BG and Roberta AG (2007). Bcl-2 family members and apoptosis, taken to heart. Am J Physiol Cell Physiol., 292:45-51.
8. Zinkel S, Gross A and Yang E (2006). BCL2 family in DNA damage and cell cycle control. Cell Death and Differentiation, 13, 1351–1359.
9. Peng J, Wenjing D and Mian W (2007). p53 and BAD: Remote strangers become close friends, Cell Research, 17: 283–285.
Antimicrobial and Related Peptides
Definition
Antimicrobial peptides (AMPs) are as widespread as bacterial inactivator molecules in the innate immune systems of insects, fungi, plants, and mammals. These peptides are also known as host defense peptides (HDPs) as they have other immuno-modulatory functions besides the direct antimicrobial actions and are even capable of killing cancerous cells 1,2.
Classification
Three broad categories of HDPs have been identified: 1) the linear peptides with helical structures, 2) the cysteine stabilized peptides with beta-sheet, and 3) a group of linear peptides rich in proline and arginine that primarily have been identified in non-mammalian species.
Structural characteristics
In mammals, cathelicidins and defensins are the two principal AMP families. Cathelicidins are peptides with a conserved proregion and a variable C-terminal antimicrobial domain. Defensins are the best-characterized AMPs, they have six invariant cysteines, forming three intramolecular cystine-disulfide bonds.
Mode of action
The mode of action of AMPs elucidated to date include inhibition of cell wall formation, formation of pores in the cell membrane resulting in the disruption of membrane potential with eventual lysis of the cell. These peptides also inhibit nuclease activity of both RNase and DNase.
Functions
They have a broad ability to kill microbes. AMPs form an important means of host defense in eukaryotes. Large AMPs (>100 amino acids), are often lytic, nutrient-binding proteins or specifically target microbial macromolecules. Small AMPs act by disrupting the structure of microbial cell membranes. It plays an active role in wound repair and regulation of the adaptive immune system. They have multiple roles as mediators of inflammation with impact on epithelial and inflammatory cells, influencing diverse processes such as cell proliferation, wound healing, cytokine release, chemotaxis, immune induction 3.
References
1. Gottlieb CT, Thomsen LE, Ingmer H, Mygind PH, Kristensen HH, Gram L(2008). Antimicrobial peptides effectively kill a broad spectrum of Listeria monocytogenes and Staphylococcus aureus strains independently of origin, sub-type, or virulence factor expression. BMC Microbiol., 8:205.
2. Yeaman MR and Yount NY (2003). Mechanisms of Antimicrobial Peptide Action and Resistance. Pharmocological Reviews, 55(1).
3. Hanna Galkowska H and Olszewski WL (2003). Antimicrobial peptides – their role in immunity and therapeutic potential. Centr Eur J Immunol., 28 (3):138–141.
Antimicrobial peptides (AMPs) are as widespread as bacterial inactivator molecules in the innate immune systems of insects, fungi, plants, and mammals. These peptides are also known as host defense peptides (HDPs) as they have other immuno-modulatory functions besides the direct antimicrobial actions and are even capable of killing cancerous cells 1,2.
Classification
Three broad categories of HDPs have been identified: 1) the linear peptides with helical structures, 2) the cysteine stabilized peptides with beta-sheet, and 3) a group of linear peptides rich in proline and arginine that primarily have been identified in non-mammalian species.
Structural characteristics
In mammals, cathelicidins and defensins are the two principal AMP families. Cathelicidins are peptides with a conserved proregion and a variable C-terminal antimicrobial domain. Defensins are the best-characterized AMPs, they have six invariant cysteines, forming three intramolecular cystine-disulfide bonds.
Mode of action
The mode of action of AMPs elucidated to date include inhibition of cell wall formation, formation of pores in the cell membrane resulting in the disruption of membrane potential with eventual lysis of the cell. These peptides also inhibit nuclease activity of both RNase and DNase.
Functions
They have a broad ability to kill microbes. AMPs form an important means of host defense in eukaryotes. Large AMPs (>100 amino acids), are often lytic, nutrient-binding proteins or specifically target microbial macromolecules. Small AMPs act by disrupting the structure of microbial cell membranes. It plays an active role in wound repair and regulation of the adaptive immune system. They have multiple roles as mediators of inflammation with impact on epithelial and inflammatory cells, influencing diverse processes such as cell proliferation, wound healing, cytokine release, chemotaxis, immune induction 3.
References
1. Gottlieb CT, Thomsen LE, Ingmer H, Mygind PH, Kristensen HH, Gram L(2008). Antimicrobial peptides effectively kill a broad spectrum of Listeria monocytogenes and Staphylococcus aureus strains independently of origin, sub-type, or virulence factor expression. BMC Microbiol., 8:205.
2. Yeaman MR and Yount NY (2003). Mechanisms of Antimicrobial Peptide Action and Resistance. Pharmocological Reviews, 55(1).
3. Hanna Galkowska H and Olszewski WL (2003). Antimicrobial peptides – their role in immunity and therapeutic potential. Centr Eur J Immunol., 28 (3):138–141.
Subscribe to:
Posts (Atom)