PTPe (RPTPe and Cyt-PTPe)
Phosphorylation of tyrosine residues in proteins is one of the better-studied molecular mechanisms for regulating protein structure and function and with it – the function of cells and organisms. Tyrosine phosphorylation is a reversible process that is controlled by the opposing activities of protein tyrosine kinases (PTKs) and protein tyrosine phosphatases (PTPs). The numbers of PTKs and PTPs are similar and small relative to the numbers of their potential substrates; there are 81 and 85 genes that yield active, protein-specific PTPs and PTKs, respectively (Alonso et al. 2004). As a result, individual PTPs and PTKs each target multiple substrates and fulfill distinct roles in different physiological systems. Although PTPs were first described in molecular terms in 1988, about a decade after PTKs, both protein superfamilies are now recognized as critical regulators of protein...