SH3GLB, a new endophilin-related protein family featuring an SH3 domain

A new cDNA encoding a protein of 362 amino acids designated SH3GLB1, for SH Y domain GRB2-like endophilin B1, was identified in a yeast two-hybrid scre en devoted to the identification of new partners interacting with the apopt osis inducer Bax. SR3GLB1 shows strong similarities to the SH3 domain-conta ining proteins of the endophilin family and presumably represents the human homologue of the potential Caenorhabditis elegans SH3 containing-protein i dentified by systematic translation of the C. elegans genome (GenBank Acces sion No. U46675). Reversing prey to bait in the yeast screen, a second prot ein, SH3GLB2, of 395 amino acids showing 65% identity to SH3GLB1 was identi fied as an interacting partner of SH3GLB1. The discovery of SH3GLB1 itself in the screening with SH3GLB1 as a bait and further mapping experiments dem onstrated that a core coiled-coil-type region is required for the formation of SH3GLB homo- and/or heterodimers, whereas the SH3 domain is not involve d in these interactions. Interestingly, the similarities with the endophili n proteins cover the entire sequence of the SH3GLB family, suggesting a com mon fold and presumably a common mode of action. Furthermore, SH3GLB member s colocalize to the cytoplasmic compartment of the cell together with Bax a nd are excluded from the nucleus. SH3GLB1 and SH3GLB2 do not significantly influence the onset and time course of Bax-mediated apoptosis in HeLa or 29 3T cells. (C) 2001 Academic Press.