Inositol Polyphosphate-5-Phosphatase F (INPP5F)

INPP5F is an inositol 1,4,5-trisphosphate (InsP3) 5-phosphatase and contains a Sac domain. The activity of this protein is specific for phosphatidylinositol 4,5-bisphosphate and phosphatidylinositol 3,4,5-trisphosphate. Alternatively spliced transcript variants have been observed, but most of them are not thought to be protein-coding.

INPP5F expressed in insect cells showed 5-phosphatase activity against phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2) and PtdIns(3,4,5)P3, similar to that of type II phosphatases. It did not hydrolyze other inositol phosphates. High activity was maintained between pH 5.5 and 8.0, with maximal activity at pH 6.0. Activity was increased in the presence of Mg(2+) and K+, but not Mn(2+), Ca(2+), or EDTA.