Catalytic inositol polyphosphate 5-phosphatase (INPP5c) domain of Inositol polyphosphate-5-phosphatase E and related proteins.
INPP5c domain of Inositol polyphosphate-5-phosphatase E (also called type IV or 72 kDa 5-phosphatase), rat pharbin, and related proteins. This subfamily 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. INPP5E hydrolyzes the 5-phosphate from PI(3,5)P2, PI(4,5)P2 and PI(3,4,5)P3, forming PI3P, PI4P, and PI(3,4)P2, respectively. It is a very potent PI(3,4,5)P3 5-phosphatase. Its intracellular localization is chiefly cytosolic, with pronounced perinuclear/Golgi localization. INPP5E also has an N-terminal proline rich domain (PRD) and a C-terminal CAAX motif. This protein is expressed in a variety of tissues, including the breast, brain, testis, and haemopoietic cells. It is differentially expressed in several cancers, for example, it is up-regulated in cervical cancer and down-regulated in stomach cancer. It is a candidate target for therapeutics of obesity and related disorders, as it is expressed in the hypothalamus, and following insulin stimulation, it undergoes tyrosine phosphorylation, associates with insulin receptor substrate-1, -2, and PI3-kinase, and become active as a 5-phosphatase. INPP5E may play a role, along with other 5-phosphatases SHIP2 and SKIP, in regulating glucose homoeostasis and energy metabolism. Mice deficient in INPPE5 develop a multi-organ disorder associated with structural defects of the primary cilium.
Jiyao W et al.(2023). "The conserved domain database in 2023.",