Zhao J, Pei G, Huang Y L, Zhong F M, Ma L
National Laboratory of Medical Neurobiology, Shanghai Medical University, China.
Biochem Biophys Res Commun. 1997 Sep 8;238(1):71-6. doi: 10.1006/bbrc.1997.7242.
The wild-type delta opioid receptor (DOR) and a carboxyl terminus-truncated mutant DOR lacking the last 31 amino acids (DOR-T) were expressed in neuroblastoma x glioma hybrid NG108-15 cells to investigate the role of the carboxyl terminus of DOR in agonist-dependent receptor phosphorylation. Stimulation of the cells with delta specific agonists significantly induced DOR phosphorylation whereas no phosphorylation of DOR-T was detected under the same conditions. Neither overexpression of G protein-coupled receptor kinases (GRK2 or GRK5) nor activation of protein kinase C promoted agonist-induced phosphorylation of DOR-T, in contrast to their strong stimulatory effect on the agonist-dependent phosphorylation of DOR. Furthermore, DOR-T failed to be internalized after agonist stimulation, probably due to its inability to be phosphorylated. Our results indicate that the carboxyl terminus of DOR is required for agonist-dependent receptor phosphorylation and the phosphorylation site(s) of DOR is likely located at its carboxyl terminus.
将野生型δ阿片受体（DOR）和缺少最后31个氨基酸的羧基末端截短突变体DOR（DOR-T）在神经母细胞瘤x胶质瘤杂交NG108-15细胞中表达，以研究DOR羧基末端在激动剂依赖性受体磷酸化中的作用。用δ特异性激动剂刺激细胞可显著诱导DOR磷酸化，而在相同条件下未检测到DOR-T的磷酸化。与它们对DOR激动剂依赖性磷酸化的强烈刺激作用相反，G蛋白偶联受体激酶（GRK2或GRK5）的过表达或蛋白激酶C的激活均未促进激动剂诱导的DOR-T磷酸化。此外，激动剂刺激后DOR-T未能内化，可能是由于其无法被磷酸化。我们的结果表明，DOR的羧基末端是激动剂依赖性受体磷酸化所必需的，且DOR的磷酸化位点可能位于其羧基末端。
