MU-OPIATE RECEPTOR - CDNA CLONING AND EXPRESSION

Mu opiate receptors recognize morphine with high affinity. A 2.1-kb ra t brain cDNA whose predicted translation product displays 63% identity with recently described delta and kappa opiate receptor sequences was identified through polymerase chain reaction and cDNA homology approa ches. This cDNA recognizes a 10.5-kb mRNA that is expressed in thalami c neurons. COS-cell expression confers naloxonazine-, Na+-, and GTP-se nsitive binding of mu but not delta or kappa opioid ligands. Expressin g cells bind morphine, [D-Ala2,N-methyl-Phe4,glyol5]enkephalin (DAMGO) , and [D-Ala2,D-Leu5]enkephalin (DADLE) with nanomolar or sub-nanomola r affinities, defining a mu opiate receptor that avidly recognizes ana lgesic and euphoric opiate drugs and opioid peptides.