CLONING AND CHARACTERIZATION OF BAP3 (BAI-ASSOCIATED PROTEIN-3), A C2DOMAIN-CONTAINING PROTEIN THAT INTERACTS WITH BAI1

BAI1 (brain-specific angiogenesis inhibitor 1), a p53-target gene spec ifically expressed in brain, encodes a seven-span transmembrane protei n considered to be a member of the secretin receptor family. Using a t wo-hybrid system, we isolated a cDNA encoding a product that interacts with the cytoplasmic region of BAI1 and designated it BAP3 (BAI1-asso ciated protein 3). The BAP3 product is a novel C2 domain-containing mo lecule with homology to Munc13 and synaptotagmin. As with Munc13, BAP3 is expressed predominantly in brain. Deletion-mutant analysis reveale d that the interaction between BAI1 and BAP3 was not mediated by the C a domains. Its predominant expression in brain and homology to Munc13 indicate that BAP3, by interacting with BAI1, might be involved in som e neuronal function such as regulating release of neurotransmitters. ( C) 1998 Academic Press.