The recently deorphanized GPR80 (GPR99) proposed to be the P2Y(15) receptor is not a genuine P2Y receptor

The P2Y receptor family currently encompasses eight members (P2Y(1,2,4,6,11,12,13,14) receptors) that are activated by extracellular adenine and/or uracil nucleotides, or, in the case of the P2Y(14) receptor, by sugar-nucleotides, and are each characterized by the typical seven-transmembrane domain topology of G-protein-coupled receptors (GPCRs) [1]. For several years, it has been known that a series of 'orphan' GPCRs (i.e. cloned receptors available in the public database for which a natural ligand has not yet been identified) share significant sequence identity with the eight genuine P2Y receptors [1,2] and thus putatively represent novel members of the P2Y receptor family.