The Bin/Amphiphysin/Rvs (BAR) domain of ArfGAP with SH3 domain, ANK repeat and PH domain containing protein 2
BAR domains are dimerization, lipid binding and curvature sensing modules found in many different proteins with diverse functions. ASAP2 (ArfGAP with SH3 domain, ANK repeat and PH domain containing protein 2) is also known as DDEF2 (Development and Differentiation Enhancing Factor 2), AMAP2, centaurin beta-3, or PAG3. ASAP2 mediates the functions of Arf GTPases vial dual mechanisms: it exhibits GTPase activating protein (GAP) activity towards class I (Arf1) and II (Arf5) Arfs; and binds class III Arfs (GTP-Arf6) stably without GAP activity. It binds paxillin and is implicated in Fcgamma receptor-mediated phagocytosis in macrophages and in cell migration. ASAP2 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.