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Originally published In Press as doi:10.1074/jbc.M611258200 on June 12, 2007
J. Biol. Chem., Vol. 282, Issue 31, 22315-22323, August 3, 2007
Phosphorylation of the -Opioid Receptor Regulates Its -Arrestins Selectivity and Subsequent Receptor Internalization and Adenylyl Cyclase Desensitization*
Yu Qiu1,
Horace H. Loh2, and
Ping-Yee Law3
From the
Department of Pharmacology, University of Minnesota Medical School, Minneapolis, Minnesota 55455
In the current study, we investigated the role of receptor phosphorylation and -arrestins in -opioid receptor (DOR) signaling and trafficking by using a DOR mutant in which all Ser/Thr residues in the C terminus were mutated to Ala (DTS). We demonstrated that the DOR agonist D-[Pen2,Pen5]enkephalin could induce receptor internalization and adenylyl cyclase (AC) desensitization of DTS, but with comparatively slower kinetics than those observed with wild type DOR. Blockade of the internalization of DTS by the dominant-negative mutant dynamin, dynamin K44E, did not affect AC desensitization. However, depletion of -arrestins almost totally blocked both internalization and AC desensitization of DTS. A BRET assay suggested that DOR phosphorylation promotes receptor selectivity for -arrestin 2 over -arrestin 1. Furthermore, in mouse embryonic fibroblast (MEF) cells lacking either -arrestin 1 ( arr1–/–) or -arrestin 2 ( arr2–/–), agonist-induced DTS desensitization and internalization were similar to that observed in wild type MEFs. In contrast, although DOR internalization decreased in both arr1–/– MEFs and arr2–/– MEFs, DPDPE-induced DOR desensitization was significantly reduced in arr2–/– MEFs, but not in arr1–/– MEFs. Additionally, the BRET assay suggested that depletion of phosphorylation did not influence the stability of the receptor- -arrestin complex. Consistent with this observation, DTS did not recycle after internalization, which is like wild type DOR. Taken together, these results indicate that receptor phosphorylation confers DOR selectivity for -arrestin 2 without affecting the stability of the receptor- -arrestin complex and the fate of the internalized receptor.
Received for publication, December 7, 2006
, and in revised form, June 7, 2007.
* This work was supported in part by National Institutes of Health Grants DA007339, DA016674, DA000564, and DA011806. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
2 Recipient of National Institutes of Health Grant K05-DA70544.
3 Recipient of National Institutes of Health Grant K05-DA00513.
1 To whom correspondence should be addressed: 6-120 Jackson Hall, 321 Church St. S.E., Minneapolis, MN 55455-0217. Tel.: 612-626-6539; Fax: 612-625-8408; E-mail: qiuxx014{at}umn.edu.

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Copyright © 2007 by the American Society for Biochemistry and Molecular Biology.
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