The Bin/Amphiphysin/Rvs (BAR) domain of ArfGAP with SH3 domain, ANK repeat and PH domain containing proteinsBAR domains are dimerization, lipid binding and curvature sensing modules found in many different proteins with diverse functions. This subfamily is composed of ASAPs (ArfGAP with SH3 domain, ANK repeat and PH domain containing proteins), which are Arf GTPase activating proteins (GAPs) with similarity to ACAPs (ArfGAP with Coiled-coil, ANK repeat and PH domain containing proteins) in that they contain an N-terminal BAR domain, followed by a Pleckstrin homology (PH) domain, an Arf GAP domain, and ankyrin (ANK) repeats. However, ASAPs contain an additional C-terminal SH3 domain. ASAPs function in regulating cell growth, migration, and invasion. Vertebrates contain at least three members, ASAP1, ASAP2, and ASAP3. ASAP1 and ASAP2 shows GTPase activating protein (GAP) activity towards Arf1 and Arf5. They do not show GAP activity towards Arf6, but is able to mediate Arf6 signaling by binding stably to GTP-Arf6. ASAP3 is an Arf6-specific GAP. BAR domains form dimers that bind to membranes, induce membrane bending and curvature, and may also be involved in protein-protein interactions. The BAR domain of ASAP1 mediates membrane bending, is essential for function, and autoinhibits GAP activity by interacting with the PH and/or Arf GAP domains.