The Bin/Amphiphysin/Rvs (BAR) domain of Endophilin-B1
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. Endophilin-B proteins are cytoplasmic proteins expressed mainly in the heart, placenta, and skeletal muscle. Endophilin-B1, also called Bax-interacting factor 1 (Bif-1) or SH3GLB1 (SH3-domain GRB2-like endophilin B1), is localized mainly to the Golgi apparatus. It is involved in the regulation of many biological events including autophagy, tumorigenesis, nerve growth factor (NGF) trafficking, neurite outgrowth, mitochondrial outer membrane dynamics, and cell death. Endophilin-B1 forms homo- and heterodimers (with endophilin-B2) through its BAR domain, which can bind and bend membranes. It interacts with amphiphysin 1 and dynamin 1 through its SH3 domain.