Human μ opiate receptor: cDNA and genomic clones, pharmacologic characterization and chromosomal assignment

A human μ opiate receptor cDNA has been identified from a cerebral cortical cDNA library using sequences from the rat μ opiate receptor cDNA. The human μ opiate receptor (hμOR1) shares 95% amino acid identity with the rat sequence. The expressed μOR1 recognizes tested opiate drugs and opioid peptides in a sodium- and GTP-sensitive fashion with affinities virtually identical to those displayed by the rat μ opiate receptor. Effects on cyclic AMP are similar to those noted for the rat μ opiate receptor. An 18 kb genomic clone hybridizing with the hμOR1 cDNA contains 63 and 489 bp exonic sequences flanked by splice donor/acceptor sequences. Analysis of hybridization to DNA prepared from human rodent hybrid cell lines and chromosomal in situ hybridization studies indicate localization to 6q24–25. An MspI polymorphism, producing a 3.7 kb band, may prove useful in assessing this gene's involvement in neuropsychiatric disorders involving opiatergic systems.