Protein tyrosine phosphatase
Protein tyrosine phosphatases (EC 3.1.3.48, systematic name protein-tyrosine-phosphate phosphohydrolase) are a group of enzymes that remove phosphate groups from phosphorylated tyrosine residues on proteins: [a protein]-tyrosine phosphate + H2O = [a protein]-tyrosine + phosphate Protein tyrosine (pTyr) phosphorylation is a common post-translational modification that can create novel recognition motifs for protein interactions and cellular localization, affect protein stability, and regulate enzyme activity. As a consequence, maintaining an appropriate level of protein tyrosine phosphorylation is essential for many cellular functions. Tyrosine-specific protein phosphatases (PTPase; ) catalyse the removal of a phosphate group attached to a tyrosine residue, using a cysteinyl-phosphate enzyme intermediate. These enzymes are key regulatory components in signal transduction pathways (such as the MAP kinase pathway) and cell cycle control, and are important in the control of cell growth, proliferation, differentiation, transformation, and synaptic plasticity. Together with tyrosine kinases, PTPs regulate the phosphorylation state of many important signalling molecules, such as the MAP kinase family. PTPs are increasingly viewed as integral components of signal transduction cascades, despite less study and understanding compared to tyrosine kinases. PTPs have been implicated in regulation of many cellular processes, including, but not limited to: Cell growth Cellular differentiation Mitotic cycles Oncogenic transformation Receptor endocytosis PTP activity can be found in four protein families. Links to all 107 members of the protein tyrosine phosphatase family can be found in the template at the bottom of this article. The class I PTPs, are the largest group of PTPs with 99 members, which can be further subdivided into 38 classical PTPs 21 receptor tyrosine phosphatases 17 nonreceptor-type PTPs 61 VH-1-like or dual-specific phosphatases (DSPs) 11 MAPK phosphatases (MPKs) 3 Slingshots 3 PRLs 4 CDC14s 19 atypical DSPs 5 phosphatase and tensin homologs (PTENs) 16 myotubularins Dual-specificity phosphatases (dTyr and dSer/dThr) dual-specificity protein-tyrosine phosphatases.
