A common event in cellular signal transduction pathways is the phosphorylation of proteins on tyrosine residues. Tyrosine phosphorylation is reversible. The forward reaction is mediated by protein tyrosine kinases. By contrast, the reverse reaction is performed by protein tyrosine phosphatases (PTP). The PTP family consists of 107 genes whose protein products are diverse in form and specificity (Alonso et al. 2004). PTPN3 and PTPN4 constitute two members of this family that were initially identified by PCR amplification using primers specific to conserved regions of the catalytic domain of canonical PTP. PTPN3 was initially cloned from a HeLa cell cDNA library, whereas PTPN4 was cloned from a megakaryoblastic cell line, (Gu et al. 1991; Yang and Tonks 1991). PTPN3 and PTPN4 are 50% identical and 67% homologous at the amino acid level.
Structure and Expression Studies
PTPN3 and PTPN4 are cytosolic proteins that localize to the...
- Patrignani C, Lafont DT, Muzio V, Greco B, Hooft van Huijsduijnen R, Zaratin PF. Characterization of protein tyrosine phosphatase H1 knockout mice in animal models of local and systemic inflammation. J Inflamm. 2010;7:16. Lond.Google Scholar
- Young JA, Becker AM, Medeiros JJ, Shapiro VS, Wang A, Farrar JD, et al. The protein tyrosine phosphatase PTPN4/PTP-MEG1, an enzyme capable of dephosphorylating the TCR ITAMs and regulating NF-kappaB, is dispensable for T cell development and/or T cell effector functions. Mol Immunol. 2008;45(14):3756–66.PubMedGoogle Scholar