INPP5D
Description
The INPP5D (inositol polyphosphate-5-phosphatase D) is a protein-coding gene located on chromosome 2.
Src homology 2 (SH2) domain containing inositol polyphosphate 5-phosphatase 1 (SHIP1) is an enzyme with phosphatase activity. SHIP1 is structured by multiple domain and is encoded by the INPP5D gene in humans. SHIP1 is expressed predominantly by hematopoietic cells but also, for example, by osteoblasts and endothelial cells. This phosphatase is important for the regulation of cellular activation. Not only catalytic but also adaptor activities of this protein are involved in this process. Its movement from the cytosol to the cytoplasmic membrane, where predominantly performs its function, is mediated by tyrosine phosphorylation of the intracellular chains of cell surface receptors that SHIP1 binds. Insufficient regulation of SHIP1 leads to different pathologies.
== Structure and regulation of activity == SHIP1 is a 145 kDa large protein and member of the inositol polyphosphate-5-phosphatase (INPP5) family. Alternate transcriptional splice variants, encoding different isoforms, have been characterized. At the N-terminus of the protein, SH2 domain is formed.
Phosphatidylinositol (PtdIns) phosphatase that specifically hydrolyzes the 5-phosphate of phosphatidylinositol-3,4,5-trisphosphate (PtdIns(3,4,5)P3) to produce PtdIns(3,4)P2, thereby negatively regulating the PI3K (phosphoinositide 3-kinase) pathways. Also hydrolyzes the 5-phosphate of phosphatidylinositol-4,5-bisphosphate (PtdIns(4,5)P3) and inositol 1,3,4,5-tetrakisphosphate. Acts as a negative regulator of B-cell antigen receptor signaling. Mediates signaling from the FC-gamma-RIIB receptor (FCGR2B), playing a central role in terminating signal transduction from activating immune/hematopoietic cell receptor systems. Acts as a negative regulator of myeloid cell proliferation/survival and chemotaxis, mast cell degranulation, immune cells homeostasis, integrin alpha-IIb/beta-3 signaling in platelets and JNK signaling in B-cells. Regulates proliferation of osteoclast precursors, macrophage programming, phagocytosis and activation and is required for endotoxin tolerance. Involved in the control of cell-cell junctions, CD32a signaling in neutrophils and modulation of EGF-induced phospholipase C activity. Key regulator of neutrophil migration, by governing the formation of the leading edge and polarization required for chemotaxis. Modulates FCGR3/CD16-mediated cytotoxicity in NK cells. Mediates the activin/TGF-beta-induced apoptosis through its Smad-dependent expression.
INPP5D is also known as SHIP, SHIP-1, SHIP1, SIP-145, hp51CN, p150Ship.
