The Bin/Amphiphysin/Rvs (BAR) domain of Endophilin-B2
BAR domains are dimerization, lipid binding and curvature sensing modules found in many different proteins with diverse functions. Endophilins play roles in synaptic vesicle formation, virus budding, mitochondrial morphology maintenance, receptor-mediated endocytosis inhibition, and endosomal sorting. Endophilins contain an N-terminal N-BAR domain (BAR domain with an additional N-terminal amphipathic helix), followed by a variable region containing proline clusters, and a C-terminal SH3 domain. They are classified into two types, A and B. Vertebrates contain two endophilin-B isoforms. Endophilin-B proteins are cytoplasmic proteins expressed mainly in the heart, placenta, and skeletal muscle. Endophilin-B2, also called SH3GLB2 (SH3-domain GRB2-like endophilin B2), is a cytoplasmic protein that interacts with the apoptosis inducer Bax. It is overexpressed in prostate cancer metastasis and has been identified as a cancer antigen with potential utility in immunotherapy. Endophilin-B2 forms homo- and heterodimers (with endophilin-B1) through its BAR domain, which can bind and bend membranes.