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General Comment |
G protein-coupled receptors (GPCRs) share a common structure of 7 transmembrane domains, an extracellular N-terminal
domain, an intracellular C-terminal domain, and several conserved residues. Family C of the GPCR superfamily consists of
metabotropic glutamate receptor-like proteins (e.g., GRM2; OMIM 604099).
By searching sequence databases for metabotropic glutamate receptor homologs,Robbins et al. (2000) and
Brauner-Osborne and Krogsgaard-Larsen (2000) identified cDNAs encoding GPRC5B, or RAIG2. GPRC5B is a 403-amino acid protein or a 395-amino acid protein encoded by 3
exons. The GPRC5B protein contains 7 predicted transmembrane helices and conserved cysteines characteristic of GPCRs.
It also contains a predicted signal peptide and a potential N-glycosylation site. GPRC5B shares 43% and 38% amino acid identity with GPRC5C (605949) and RAIG1 (RAI3; 604138), respectively.
GPRC5B belongs to family C, group 5, of the GPCR superfamily. In
contrast to other members of family C, GPRC5B has a short N-terminal domain, and Brauner-Osborne and Krogsgaard-Larsen (2000) hypothesized that it may represent a novel subgroup of family C receptors. Using a PCR-based
expression analysis, GPRC5B transcripts were found at highest levels in brain, with most abundant
expression in corpus callosum, caudate nucleus, putamen, substantia nigra, thalamus,and spinal cord. Using
RT-PCR, Brauner-Osborne and Krogsgaard-Larsen (2000) ] detected widespread expression of GPRC5B, with highest
levels in kidney, pancreas, and testis, and medium levels in brain, heart, prostate, small intestine, and spleen.
This orphan receptor was found in a human ovary cDNA library.
NCBI Summary:
The protein encoded by this gene is a member of the type 3 G protein-coupled receptor family. Members of this superfamily are characterized by a signature 7-transmembrane domain motif. The specific function of this protein is unknown; however, this protein may mediate the cellular effects of retinoic acid on the G protein signal transduction cascade.
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