GTPase-activating protein (GAP) for ARF1 and ARF5, which also shows strong GTPase activity. Participates in the prevention of neuronal apoptosis by enhancing PI3 kinase activity. Aids the coupling of metabotropic glutamate receptor 1 (GRM1) to cytoplasmic PI3 kinase by interacting with Homer scaffolding proteins, and also seems to mediate anti-apoptotic effects of NGF by activating nuclear PI3 kinase (By similarity). GAP activity is stimulated by phosphatidylinositol 4,5-bisphosphate (PIP2) and, to a lesser extent, by phosphatidylinositol 3,4,5-trisphosphate (PIP3). Phosphatidic acid potentiates PIP2 stimulation (By similarity). Interacts with EPB41L1, PLCG1, NF2, HOMER1 and HOMER2. G domain binds GTP and has GTPase activity. Arf-GAP domain interacts with G domain and may regulate its GTPase activity. PH domain binds phospholipids and is required for nuclear targeting. Belongs to the centaurin gamma-like family.