Inositol Polyphosphate-5-Phosphatase 72kDa (INPP5E)

INPP5E is an inositol 1,4,5-trisphosphate (InsP3) 5-phosphatase. InsP3 5-phosphatases hydrolyze Ins(1,4,5)P3, which mobilizes intracellular calcium and acts as a second messenger mediating cell responses to various stimulation. Studies of the mouse counterpart suggest that this protein may hydrolyze phosphatidylinositol 3,4, 5-trisphosphate and phosphatidylinositol 3,5-bisphosphate on the cytoplasmic Golgi membrane and thereby regulate Golgi-vesicular trafficking.

INPP5E expressed in insect cells readily hydrolyzed PtdIns(3,4,5)P3 to PtdIns(3,4)P2 in a time- and concentration-dependent manner. It did not hydrolyze soluble inositol phosphate or other inositol lipids. Altering the detergent composition of the assay permitted INPP5E-mediated hydrolysis of PtdIns(4,5)P2 to PtdIns(4)P.