Structure and chromosomal mapping of genes for the mouse kappa-opioid receptor and an opioid receptor homologue (MOR-C).

Recent cDNA cloning studies have defined four members of the opioid receptor family, i.e., delta-, mu- and kappa-subtypes, and an opioid receptor homologue for unknown ligands. In this report, we isolated and analyzed mouse genomic DNA segments containing the kappa-opioid receptor gene and a gene for the opioid receptor homologue (designated as MOR-C). The genes are closely related each other in exon-intron organization, suggesting their evolutional relationship. Using in situ hybridization, we show that the kappa-opioid receptor gene and the MOR-C gene map to mouse chromosome 1A2-3 and 2H2-4, respectively.