Controls the cellular levels and subcellular distribution of phosphatidylinositol 3-phosphate and phosphatidylinositol 4,5-bisphosphate. Involved in distinct membrane trafficking and signal transduction pathways. Highly active against a range of soluble and lipid inositol phosphates. Active in dephosphorylating the 5-position of Ins(1,4,5)P3 and Ins(1,3,4,5)P4 and to a lesser extent Ins(1,4,5,6)P4. The enzyme is also active against PI(4,5)P2 presented in sonicated vesicles and Triton mixed micelles, and somewhat less active against PI(3,5)P2 in unilamellar vesicles. Activity against PI(3,5)P2 drops sharply when this substrate is presented in mixed micelles. Also hydrolyzes PIP3 to produce PI(3,4)P2. a 1,2-diacyl-sn-glycero-3-phospho-(1D-myo-inositol-4,5-bisphosphate) + H2O = a 1,2-diacyl-sn-glycero-3-phospho-(1D-myo-inositol 4-phosphate) + phosphate Optimum pH is about 7.4. Localizes at the cell tip and the barrier septum. Belongs to the synaptojanin family. In the central section; belongs to the inositol 1,4,5-trisphosphate 5-phosphatase family.