Cloning and expression of a cDNA for the rat k‐opioid receptor

Abstract
We cloned a cDNA for the rat K‐opioid receptor from a rat thalamus cDNA library. The deduced amino acid sequence consists of 380 residues with features shared by members of the G protein‐coupled receptor family. The specific binding of [3H]bremazocine to the membrane of COS‐7 cells transfected with the cDNA was displaced by k‐specific opioid ligands, but not by μ‐ and δ‐specific ligands. Xenopus oocytes injected with the in vitro transcribed mRNA responded to opioid ligands with the same subtype specificity. Northern blot analysis demonstrated that k‐opioid receptor mRNA is expressed in a regionally specific manner in rat brain.