Inositol Polyphosphate-5-Phosphatase J (INPP5J)

PIB5PA contains a putative SH3-binding motif, six 14-3-3 binding motifs, and 2 catalytic motifs that are conserved in other 5-phosphatases. Northern blot analysis detected PIB5PA in brain, heart, kidney, stomach, small intestine, and lung. Expression was also detected in a variety of human, rat, and mouse cell lines. Because PIB5PA hydrolyzed phosphate at the D-5 position of PtdIns(4,5)P2, Ins(1,4,5)P3, and Ins(1,3,4,5)P4, Mochizuki and Takenawa (1999) classified it as a type II 5-phosphatase. PIB5PA localizes in the cytoplasm and at ruffling membranes.PIB5PA does not participate in the reorganization of the actin cytoskeleton but may be involved in modulation of the function of inositol and phosphatidylinositol polyphosphate-binding proteins that are present at membrane ruffles.