The ADP-ribosylation factor (ARF) family of small GTP-binding proteins are involved in vesicular transport regulation and in controlling cytoskeletal organization and cell adhesion. These proteins mainly regulate membrane traffic. ACAP2 is a member of the centaurin GTPase-activating protein (GAP) family, which comprises a subset of ARF regulatory molecules that transduce PI 3-kinase activation into coordinated control of ARF-dependent pathways. ACAP1 and ACAP2 are both widely expressed in peripheral, tubular membranes and usually interact with each other in various tissues. GAP activity of both ACAP1 and ACAP2 is dependent upon phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2]. ACAP2 associates with ARF1 and ARF6. Overexpression of ACAP2 blocks the formation of ARF6-dependent protrusions. K1L is a protein required for growth of the Vaccinia Virus that interacts with the ankyrin repeats of ACAP2.