GTPase-activating protein for ARF1 and, to a lesser extent, ARF5. Directly and specifically regulates the adapter protein 3 (AP-3)-dependent trafficking of proteins in the endosomal-lysosomal system (By similarity). GAP activity stimulated by phosphatidylinositol 3,4,5-trisphosphate (PIP3) and, to a lesser extent, by phosphatidylinositol 4,5-bisphosphate (PIP2). Phosphatidic acid potentiates PIP2 stimulation (By similarity). Homodimer. Interacts with several subunits of the AP-3 protein complex: AP3M1, AP3S1 and AP3S2. Interacts with GUCY1A3 and GUCY1B3 (By similarity). Associates with the endocytic compartment. Widely expressed, with highest levels in brain and kidney. At 12.5 dpc, expression is restricted to neural tube, forebrain and midbrain. The PH domain mediates AP-3 binding. Phosphorylated on tyrosines. Belongs to the centaurin gamma-like family.