Rationale: The paper reports the cloning of the Kappa-type opioid receptor. Figure 2 shows the displacement of (3H)-bremazocine from the membrane of COS-7 cells transfected with rat K-opiotd receptor cDNA. No binding was found in the membranes of COS-7 cells transfected with an empty vector. For displacement, the unlabeled Kappa-type specific ligands Dynorphin A and U50488H were used. A very high rate of displacement was observed by the two ligands (85% and 33%), indicating that the expressed protein encodes the kappa-type opioid receptor. The mu-type opioid receptor ligand DAMGO and the delta-type opioid receptor ligand DPDPE were inefficient in displacing the specific binding of (3H)-bremazocine.. Experimental description: 'We cloned a cDNA for the rat Ic-opioid receptor from a rat thalamus cDNA library'