Conopressin Peptide and Analogs

Definition
Conopressin is a nonapeptide that is expressed in the central nervous system and it acts like a neurotransmitter in mollusks1.

Discovery
Conopressin activity was first extracted from mollusk ganglia in 19752.

Classification
Conopressin belongs to vasopressin-like peptide family3.

Structural Characteristics
Conopressin consists of a carboxy terminal amidation signal, an endoproteoltytic processing site and a neurophysin domain4. Several structural analogs of conopressin- G,T and S have been identified4.

Mode of action
It is known that conopressins exert their functions via binding to G-protein coupled receptors4.

Functions
Conopressin affects excitability, firing, and action potential shape through stimulation of transient and persistent inward currents in mulluscan neurons1. It also modulates gill behavior1.

References
1.van Soest PF, Kits KS (1998). Conopressin affects excitability, firing, and action potential shape through stimulation of transient and persistent inward currents in molluscan neurons. J Neurophysiol, 79(4):1619-32.
2.Ifshin, M. S., Gainer, H and Barker, J. L (1975). Peptide factor extracted from molluscan ganglia that modulates bursting pacemaker activity. Nature, 254: 72–74.
3.Dutertre S, Croker D, Daly NL, Andersson A, Muttenthaler M, Lumsden NG, Craik DJ, Alewood PF, Guillon G, Lewis RJ (2008). Conopressin-T from Conus tulipa reveals an antagonist switch in vasopressin-like peptides. J Biol Chem, 283(11):7100-8.
4.Book: Structure and function of primary messengers in invertebrates. Klaus W. Beyenbach, 12-13.