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Catalytic inositol polyphosphate 5-phosphatase (INPP5c) domain of SH2 domain containing inositol polyphosphate 5-phosphatase-1 and -2, and related proteins This subfamily contains the INPP5c domain of SHIP1 (SH2 domain containing inositol polyphosphate 5-phosphatase-1, also known as SHIP/INPP5D), and SHIP2 (also known as INPPL1). 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. Both SHIP1 and -2 catalyze the dephosphorylation of the PI, phosphatidylinositol 3,4,5-trisphosphate [PI(3,4,5)P3], to phosphatidylinositol 3,4-bisphosphate [PI(3,4)P2]. SHIP1 also converts inositol-1,3,4,5- polyphosphate [I(1,3,4,5)P4] to inositol-1,3,4-polyphosphate [I(1,3,4)P3]. SHIP1 and SHIP2 have little overlap in their in vivo functions. SHIP1 is a negative regulator of cell growth and plays a major part in mediating the inhibitory signaling in B cells; it is predominantly expressed in hematopoietic cells. SHIP2 is as an inhibitor of the insulin signaling pathway, and is implicated in actin structure remodeling, cell adhesion and cell spreading, receptor endocytosis and degradation, and in the JIP1-mediated JNK pathway. SHIP2 is widely expressed, most prominently in brain, heart and in skeletal muscle. In addition to this INPP5c domain, SHIP1 has an N-terminal SH2 domain, two NPXY motifs, and a C-terminal proline-rich region (PRD), while 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 gene for conferring a predisposition for type 2 diabetes. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",