The three members of the brain angiogenesis inhibitor (BaI1-3) are receptors belonging to the adhesion subfamily of G-protein coupled receptor superfamily. Like all members of GPCRs, all three BaIs have seven transmembrane domains, an intracellular C-terminal tail and extracellular N-terminus. Like other adhesion members, the N-terminus is quite large. Many domains are localized to the N-terminus; various glycosylations sites are present, there is a GPCR proteolysis site, a putative hormone binding domain and thrombospondin type 1 repeats which regulate the anti-angiogenic activity of thrombospondin-1. The C-terminal tail interacts with PDZ-domain proteins. Unique to BaI1 is a proline-rich domain required for interacting with Src homology domains and WW domain proteins.