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Description

Receptor type protein tyrosine phosphatase sap-1 (UniProt: B6ZDS3, also known as Stomach-cancer associated protein tyrosine phosphatase 1, SAP-1) is encoded by Ptprh (also known as Sap1) gene (Gene ID: 545902) in murine species. SAP-1 is a receptor-type (R3) protein tyrosine phosphatase that is expressed predominantly in the gastrointestinal tract, most prominently in the microvilli of the brush border in gastrointestinal epithelial cells. SAP-1 has a single catalytic domain in its cytoplasmic region and eight fibronectin type III-like domains in its extracellular region. It is synthesized with a 27 amino acid signal peptide, which is subsequently cleaved. SAP-1 is reported to play a significant role in the regulation of intestinal tumorigenesis and its expression is markedly increased in colon and pancreatic cancers. Ablation of SAP-1 in IL-10-deficient mice display greater severity of colitis in association with up-regulation of mRNAs for various cytokines and chemokines in the colon. The cytoplasmic region of SAP-1 is shown to bind directly to Lck. Over-expression of SAP-1 results in down-regulation of Lck activity that leads to inhibition of T cell receptor-mediated T cell function. (Ref.: Murata, Y et al. (2015). Proc. Natl. Acad. Sci. USA. 112(31):E4264-71).