Binds specifically to phosphatidylinositol 3,4-diphosphate (PtdIns3,4P2), but not to other phosphoinositides. May recruit other proteins to the plasma membrane. Interacts with MPDZ and PTPN13. Locates to the plasma membrane after treatments that stimulate the production of PtdIns3,4P2. Highly expressed in skeletal muscle, thymus, pancreas, placenta and lung. Detected at low levels in brain, heart, peripheral blood leukocytes, testis, ovary, spinal cord, thyroid, kidney, liver, small intestine and colon. Binds to membranes enriched in PtdIns3,4P2 via the C-terminal PH domain.