title: Beta-arrestin acts as a clathrin adaptor in endocytosis of the beta2-adrenergic receptor.
abstract: The ability of a system to regulate its responsiveness in the presence of a continuous stimulus, often termed desensitization, has been extensively characterized for the beta2-adrenergic receptor (beta2AR). beta2AR signalling is rapidly attenuated through receptor phosphorylation and subsequent binding of the protein beta-arrestin. Ultimately the receptor undergoes internalization, and although the molecular mechanism is unclear, receptor phosphorylation and beta-arrestin binding have been implicated in this processs. Here we report that beta-arrestin and arrestin-3, but not visual arrestin, promote beta2AR internalization and bind with high affinity directly and stoichiometrically to clathrin, the major structural protein of coated pits. Moreover, beta-arrestin/arrestin chimaeras that are defective in either beta2AR or clathrin binding show a reduced ability to promote beta2AR endocytosis. Immunofluorescence microscopy of intact cells indicates an agonist-dependent colocalization of the beta2AR and beta-arrestin with clathrin. These results show that beta-arrestin functions as an adaptor in the receptor-mediated endocytosis pathway, and suggest a general mechanism for regulating the trafficking of G-protein-coupled receptors.
authors.affiliation: Department of Biochemistry and Molecular Pharmacology, Kimmel Cancer Institute, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA.
authors.forename: O B
authors.initials: OB
authors.lastname: Goodman
authors.forename: J G
authors.initials: JG
authors.lastname: Krupnick
authors.forename: F
authors.initials: F
authors.lastname: Santini
authors.forename: V V
authors.initials: VV
authors.lastname: Gurevich
authors.forename: R B
authors.initials: RB
authors.lastname: Penn
authors.forename: A W
authors.initials: AW
authors.lastname: Gagnon
authors.forename: J H
authors.initials: JH
authors.lastname: Keen
authors.forename: J L
authors.initials: JL
authors.lastname: Benovic
mesh_terms: D000818:Animals; D019390:Arrestins / Q000235:genetics / Q000378:metabolism*; D019556:COS Cells; D002417:Cattle; D002460:Cell Line; D002966:Clathrin / Q000378:metabolism*; D004705:Endocytosis / Q000502:physiology*; D019204:GTP-Binding Proteins / Q000378:metabolism; D011485:Protein Binding; D018343:Receptors, Adrenergic, beta-2 / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D014162:Transfection; D000071557:beta-Arrestins
chemical_list: D019390:Arrestins; D002966:Clathrin; D018343:Receptors, Adrenergic, beta-2; D011993:Recombinant Fusion Proteins; C082333:arrestin3; D000071557:beta-Arrestins; D019204:GTP-Binding Proteins