Cloning and Characterization of a Novel Orphan G-Protein-Coupled Receptor Localized to Human Chromosome 2p16

We report the identification and characterisation of a novel human orphan G-protein-coupled receptor (GPR) which maps to chromosome 2p16. We have determined the full-length coding sequence and genomic structure of a gene corresponding to the anonymous expressed sequenced tag, WI-31133. This gene encodes a novel protein that is 540 amino acids in length. Protein sequence analysis predicts the presence of seven transmembrane domains, a characteristic feature of GPRs. In situ hybridisation to human retina and Northern blot analysis of human retinal pigment epithelium (RPE) showed localisation of this transcript to the RPE and cells surrounding retinal arterioles. In contrast, the transcript was localised to the photoreceptor inner segments and the outer plexiform layer in mouse sections. Northern blot analysis demonstrated a 7 kb transcript highly expressed in the brain. No mutations were identified during a screen of patients suffering from Doyne's honeycomb retinal dystrophy (DHRD), an inherited retinal degeneration which maps to chromosome 2p16.