Binding properties of C-truncated delta opioid receptors

目的：研究δ阿片受体Ｃ末端在受体结合配体的亲和力及选择性中的作用．方法：在中国苍鼠卵巢细胞（ＣＨＯ细胞）中分别稳定表达Ｃ末端截短３１个氨基酸残基及野生型δ阿片受体，用受体结合分析法研究表达产物与配体的结合特征．结果：表达得到典型突变受体克隆ＣＨＯＴ及野生型受体克隆ＣＨＯＷ．ＣＨＯＴ结合［３Ｈ］ｄｉｐｒｅｎｏｒｐｈｉｎｅ（Ｄｉｐ）及［３Ｈ］［ＤＡｌａ２，ＤＬｅｕ５］ｅｎｋｅｐｈａｌｉｎ（ＤＡＤＬＥ）的Ｋｄ值与ＣＨＯＷ一致，δ选择性激动剂对二者与［３Ｈ］Ｄｉｐ的结合均有很强的抑制作用，且Ｋｉ相似；而μ及κ选择性激动剂则对二者均无抑制作用．结论：δ阿片受体的Ｃ末端与受体结合配体的亲和力及选择性无关．

IM: To study the role of C terminal delta opioid receptor involved in ligand binding affinity and selectivity. METHODS: The 31 amino acid residues of C terminal truncated delta opioid receptors and the wild type were expressed stably in Chinese hamster ovary (CHO) cells, respectively. 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 values of diprenorphine (Dip) and leucine 2 alanine enkephalin (DADLE) bound to CHO T were similar to CHO W. Both the specific Dip bindings of CHO T and CHO W were strongly inhibited by delta selective agonists with similar K i, but neither by mu nor kappa selective agonists. CONCLUSION: The C terminal of the delta opioid receptor is not involved in the ligands binding affinity and selectivity.