Phosphorylated Peptide

Phosphorylated Peptide

Peptides are short polymers formed from the linking, in a defined order, of α-amino acids. The link between one amino acid residue and the next is known as an amide bond or a peptide bond. Proteins are polypeptide molecules (or consist of multiple polypeptide subunits). The distinction is that peptides are short and polypeptides/proteins are long. There are several different conventions to determine these, all of which have caveats and nuances.

Protein Phosphorylation

The phosphorylation state of a protein is important to signal transduction pathways. The primary players are protein kinases that catalyze the transfer of the terminal phosphate group of ATP to acceptor protein target(s) at serine, threonine and tyrosine residues. Over 500 kinases are present in cells and roughly one fifth of these are tyrosine kinases. Kinases are involved in most aspects of cell regulation, including cell growth, differentiation and metabolism. Some kinases exert their effects through transmembrane receptors, such as the insulin receptor, while others act inside the cell.

Kinases

Kinases are important drug targets because of their involvement in so many pathways and regulatory events. Cancer, inflammation and other disruptions of normal cell regulation often can be attributed to kinase dis-regulation. Protein phosphatases play opposite roles to protein kinases by dephosphorylating the protein target.