The Bin/Amphiphysin/Rvs (BAR) domain of ArfGAP with SH3 domain, ANK repeat and PH domain containing protein 3
BAR domains are dimerization, lipid binding and curvature sensing modules found in many different proteins with diverse functions. ASAP3 (ArfGAP with SH3 domain, ANK repeat and PH domain containing protein 3) is also known as ACAP4 (ArfGAP with Coiled-coil, ANK repeat and PH domain containing protein 4), DDEFL1 (Development and Differentiation Enhancing Factor-Like 1), or centaurin beta-6. It is an Arf6-specific GTPase activating protein (GAP) and is co-localized with Arf6 in ruffling membranes upon EGF stimulation. ASAP3 is implicated in the pathogenesis of hepatocellular carcinoma and plays a role in regulating cell migration and invasion. ASAP3 contains an N-terminal BAR domain, followed by a Pleckstrin homology (PH) domain, an Arf GAP domain, ankyrin (ANK) repeats, and a C-terminal SH3 domain. 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 the related protein ASAP1 mediates membrane bending, is essential for function, and autoinhibits GAP activity by interacting with the PH and/or Arf GAP domains.