Role for the C-Terminus in Agonist-Induced Opioid Receptor Phosphorylation and Desensitization
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- 作者：Hong Bing Deng ; Yunkai Yu ; Youngshil Pak ; Brian F. O'Dowd ; Susan R. George ; Christopher K. Surratt ; George R. Uhl ; and Jia Bei Wang
- 刊名：Biochemistry
- 出版年：2000
- 出版时间：May 9, 2000
- 年：2000
- 卷：39
- 期：18
- 页码：5492 - 5499
- 全文大小：115K
- 年卷期：v.39,no.18(May 9, 2000)
- ISSN：1520-4995
文摘
Determining which domains and amino acid residues of the 
opioid receptor arephosphorylated is critical for understanding the mechanism of opioid receptor phosphorylation. Therole of the C-terminus of the receptor was investigated by examining the C-terminally truncated or point-mutated opioid receptors in receptor phosphorylation and desensitization. Both wild-type and mutatedreceptors were stably expressed in Chinese hamster ovary (CHO) cells. The receptor expression wasconfirmed by receptor radioligand binding and immunoblottting. After exposure to 5 M of DAMGO,phosphorylation of the C-terminally truncated receptor and the mutant receptor T394A was reduced to 40and 10% of that of the wild-type receptor, respectively. Mutation effects on agonist-induced desensitizationwere studied using adenylyl cyclase inhibition assays. The C-terminally truncated receptor and mutantreceptor T394A both showed complete loss of DAMGO-induced desensitization, while the mutant T/S-7A receptor only lost part of its ability to desensitize. Taken together, these results suggest that theC-terminus of the opioid receptor participates in receptor phosphorylation and desensitization withthreonine 394, a crucial residue for both features. DAMGO-induced opioid receptor phosphorylationand desensitization are associated and appear to involve both the opioid receptor C-terminus and otherdomains of the receptor.
opioid receptor arephosphorylated is critical for understanding the mechanism of opioid receptor phosphorylation. Therole of the C-terminus of the receptor was investigated by examining the C-terminally truncated or point-mutated opioid receptors in receptor phosphorylation and desensitization. Both wild-type and mutatedreceptors were stably expressed in Chinese hamster ovary (CHO) cells. The receptor expression wasconfirmed by receptor radioligand binding and immunoblottting. After exposure to 5 M of DAMGO,phosphorylation of the C-terminally truncated receptor and the mutant receptor T394A was reduced to 40and 10% of that of the wild-type receptor, respectively. Mutation effects on agonist-induced desensitizationwere studied using adenylyl cyclase inhibition assays. The C-terminally truncated receptor and mutantreceptor T394A both showed complete loss of DAMGO-induced desensitization, while the mutant T/S-7A receptor only lost part of its ability to desensitize. Taken together, these results suggest that theC-terminus of the opioid receptor participates in receptor phosphorylation and desensitization withthreonine 394, a crucial residue for both features. DAMGO-induced opioid receptor phosphorylationand desensitization are associated and appear to involve both the opioid receptor C-terminus and otherdomains of the receptor.