Bin2, a functionally nonredundant member of the BAR adaptor gene family

BAR family proteins are a unique class of adaptor proteins characterized by a common N-terminal fold of undetermined function termed the BAR domain. T his set of adaptors, which includes the mammalian proteins amphiphysin and Bin1 and the yeast proteins Rvs167p and Rvs161p, has been implicated in div erse cellular processes, including synaptic vesicle endocytosis, actin regu lation, differentiation, cell survival, and tumorigenesis. Here we report t he identification and characterization of Bin2, a novel protein that contai ns a BAR domain but that is otherwise structurally dissimilar to other memb ers of the BAR adaptor family. The Bin2 gene is located at chromosome 4q22. 1 and is expressed predominantly in hematopoietic cells. Bin2 is upregulate d during differentiation of granulocytes, suggesting that it functions in t hat lineage. Bin2 formed a stable complex in cells with Bin1, but not with amphiphysin, in a BAR domain-dependent manner. This finding indicates that BAR domains have specific preferences for interaction. However, Bin2 did no t influence endocytosis in the same manner as brain-specific splice isoform s of Bin1, nor did it exhibit the tumor suppressor properties inherent to u biquitous splice isoforms of Bin1. Thus, Bin2 appears to encode a nonredund ant function in the BAR adaptor gene family. (C) 2000 Academic Press.