Phosphatase with phosphoinositide 3'-phosphatase activity that can use phosphatidylinositol-3-phosphate (PtdIns3P) and phosphatidylinositol-3,5-diphosphate (PtdIns3,5P(2)) as substrates and produces phosphatidylinositol-5-phosphate (PtdIns5P); participates in pathway(s) that transfer gene regulatory signals to the nucleus. a 1,2-diacyl-sn-glycero-3-phospho-(1D-myo-inositol-3-phosphate) + H2O = a 1,2-diacyl-sn-glycero-3-phospho-(1D-myo-inositol) + phosphate a 1,2-diacyl-sn-glycero-3-phospho-(1D-myo-inositol-3,5-bisphosphate) + H2O = a 1,2-diacyl-sn-glycero-3-phospho-(1D-myo-inositol-5-phosphate) + phosphate Highly concentrated at the peripheral lobes of the epidermal cells. Mostly expressed in flowers and roots, and, to a lower extent, in siliques and leaves. Expressed in young seedlings, especially at the tip of the growing shoot meristems. Later observed in roots and in aerial parts. Weakly expressed in leaves with local higher levels in the trichomes and in cotyledon veins. Present at low levels in flowers with higher accumulation in cells at organ-stem junctions. Restricted to the developing peduncle. No visible phenotype in both normal and dehydration conditions. Belongs to the protein-tyrosine phosphatase family. Non-receptor class myotubularin subfamily.