Members of the G protein coupled receptor (GPCR) superfamily contain 7 transmembrane domains and transduce extracellular signals through heterotrimeric G proteins. The organization of the GPR17 gene differs from that of many other GPCRs in that the open reading frame is distributed on 2 exons; an additional exon contains the 5 prime untranslated region. Human GPR17 is expressed as 2.3 and 6.3 kb mRNAs exclusively in brain. The 2 transcripts appear to represent alternatively polyadenylated variants. Based on protein sequence homology and the conservation of certain key residues, GPR17 appears to be closely related to the P2Y family of GPCRs. There are two nemed isoforms.