BINDING-PROPERTIES OF C-TRUNCATED DELTA-OPIOID RECEPTORS

AIM: To study the role of C-terminal delta opioid receptor involved in ligand binding affinity and selectivity. METHODS: The 31 amino acid r esidues of C-terminal truncated delta opioid receptors and the wild-ty pe were expressed stably in Chinese hamster ovary (CHO) cells, respect ively. Then the ligand binding properties of the products were studied by receptor binding assay. RESULTS: A typical mutated receptor clone CHO-T and a wild-type receptor clone CHO-W were obtained. The K-d valu es of [H-3] diprenorphine (Dip) and [H-3]leucine-2-alanine enkephalin (DADLE) bound to CHO-T were similar to CHO-W. Both the specific [H-3]D ip bindings of CHO-T and CHO-W were strongly inhibited by delta select ive agonists with similar K-i, but neither by mu nor kappa selective a gonists. CONCLUSION: The C-terminal of the delta opioid receptor is no t involved in the ligands binding affinity and selectivity.