The Bin/Amphiphysin/Rvs (BAR) domain of Adaptor protein, Phosphotyrosine interaction, PH domain and Leucine zipper containing 2
BAR domains are dimerization, lipid binding and curvature sensing modules found in many different proteins with diverse functions. Adaptor protein, Phosphotyrosine interaction, PH domain and Leucine zipper containing (APPL) proteins are effectors of the small GTPase Rab5 that function in endosome-mediated signaling. They contain BAR, pleckstrin homology (PH) and phosphotyrosine binding (PTB) domains. They form homo- and hetero-oligomers that are mediated by their BAR domains. Vertebrates contain two APPL proteins, APPL1 and APPL2. Both APPL proteins interact with the transcriptional repressor Reptin, acting as activators of beta-catenin/TCF-mediated trancription. APPL2 is essential for cell proliferation. BAR domains form dimers that bind to membranes, induce membrane bending and curvature, and may also be involved in protein-protein interactions.