Dynamin and β-Arrestin Reveal Distinct Mechanisms for G Protein-coupled Receptor Internalization

doi:10.1074/jbc.271.31.18302

Dynamin and β-Arrestin Reveal Distinct Mechanisms for G Protein-coupled Receptor Internalization*

From the Howard Hughes Medical Institute Laboratories and Department of Cell Biology, Duke University Medical Center, Durham, North Carolina 27710

^¶ To whom correspondence should be addressed:
Duke University Medical Center, Box 3287, Durham, NC 27710.
Tel.: 919-684-5433; Fax: 919-681-8641.

Abstract

The process of agonist-promoted internalization (sequestration) of G protein-coupled receptors (GPCRs) is intimately linked to the regulation of GPCR responsiveness. Following agonist-mediated desensitization, sequestration of GPCR is presumably associated with the dephosphorylation and recycling of functional receptors. However, the exact mechanisms responsible for GPCR sequestration, even for the prototypic β₂-adrenergic receptor (β₂AR), have remained controversial. We demonstrate here that dynamin, a GTPase that regulates the formation and internalization of clathrin-coated vesicles, is essential for the agonist-promoted sequestration of the β₂AR, suggesting that the β₂AR internalizes via the clathrin-coated vesicle-mediated endocytic pathway. In contrast, internalization of the angiotensin II type 1A receptor (AT_1AR), another typical GPCR, does not require dynamin. In addition, the AT_1AR internalizes independent of the function of β-arrestin, a critical component for β₂AR cellular trafficking, but additional AT_1ARs are mobilized to the dynamin-dependent pathway upon overexpression of β-arrestin. These findings demonstrate that GPCRs can utilize distinct endocytic pathways, distinguishable by dynamin and β-arrestin, and that β-arrestins function as adaptor proteins specifically targeting GPCRs for dynamin-dependent endocytosis via clathrin-coated vesicles.

Footnotes

↵^‡ Recipient of a postdoctoral fellowship from the Medical Research Council of Canada.
↵^§ Recipient of a Howard Hughes postdoctoral fellowship.
↵* This work was supported in part by National Institutes of Health Grant NS 19576, an unrestricted Neuroscience Award from Bristol Myers Squibb, and an unrestricted grant from Zeneca Pharmaceutical Co. (to M. G. C.). The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
↵¹ The abbreviations used are:

GPCR

G protein-coupled receptor

β₂AR

β₂-adrenergic receptor

AT_1AR

angiotensin II type 1A receptor

HEK 293 cells

human embryonic kidney 293 cells.
- Received May 22, 1996.