Catalytic inositol polyphosphate 5-phosphatase (INPP5c) domain of SH2 domain containing inositol 5-phosphatase-2 and related proteins
This subfamily contains the INPP5c domain of SHIP2 (SH2 domain containing inositol 5-phosphatase-2, also called INPPL1) and related proteins. It belongs to a family of Mg2+-dependent inositol polyphosphate 5-phosphatases, which hydrolyze the 5-phosphate from the inositol ring of various 5-position phosphorylated phosphoinositides (PIs) and inositol phosphates (IPs), and to the large EEP (exonuclease/endonuclease/phosphatase) superfamily that contains functionally diverse enzymes that share a common catalytic mechanism of cleaving phosphodiester bonds. SHIP2 catalyzes the dephosphorylation of the PI, phosphatidylinositol 3,4,5-trisphosphate [PI(3,4,5)P3], to phosphatidylinositol 3,4-bisphosphate [PI(3,4)P2]. SHIP2 is widely expressed, most prominently in brain, heart and in skeletal muscle. SHIP2 is an inhibitor of the insulin signaling pathway. It is implicated in actin structure remodeling, cell adhesion and cell spreading, receptor endocytosis and degradation, and in the JIP1-mediated JNK pathway. Its interacting partners include filamin/actin, p130Cas, Shc, Vinexin, Interesectin 1, and c-Jun NH2-terminal kinase (JNK)-interacting protein 1 (JIP1). A large variety of extracellular stimuli appear to lead to the tyrosine phosphorylation of SHIP2, including epidermal growth factor (EGF), platelet-derived growth factor (PDGF), insulin, macrophage colony-stimulating factor (M-CSF) and hepatocyte growth factor (HGF). SHIP2 is localized to the cytosol in quiescent cells; following growth factor stimulation and /or cell adhesion, it relocalizes to membrane ruffles. In addition to this INPP5c domain, SHIP2 has an N-terminal SH2 domain, a C-terminal proline-rich domain (PRD), which includes a WW-domain binding motif (PPLP), an NPXY motif and a sterile alpha motif (SAM) domain. The gene encoding SHIP2 is a candidate for conferring a predisposition for type 2 diabetes; it has been suggested that suppression of SHIP2 may be of benefit in the treatment of obesity and thereby prevent type 2 diabetes. SHIP2 and SHIP1 have little overlap in their in vivo functions.
Jiyao W et al.(2023). "The conserved domain database in 2023.",