title: A kinase-regulated PDZ-domain interaction controls endocytic sorting of the beta2-adrenergic receptor.
abstract: A fundamental question in cell biology is how membrane proteins are sorted in the endocytic pathway. The sorting of internalized beta2-adrenergic receptors between recycling endosomes and lysosomes is responsible for opposite effects on signal transduction and is regulated by physiological stimuli. Here we describe a mechanism that controls this sorting operation, which is mediated by a family of conserved protein-interaction modules called PDZ domains. The phosphoprotein EBP50 (for ezrinradixin-moesin(ERM)-binding phosphoprotein-50) binds to the cytoplasmic tail of the beta2-adrenergic receptor through a PDZ domain and to the cortical actin cytoskeleton through an ERM-binding domain. Disrupting the interaction of EBP50 with either domain or depolymerization of the actin cytoskeleton itself causes missorting of endocytosed beta2-adrenergic receptors but does not affect the recycling of transferrin receptors. A serine residue at position 411 in the tail of the beta2-adrenergic receptor is a substrate for phosphorylation by GRK-5 (for G-protein-coupled-receptor kinase-5) and is required for interaction with EBP50 and for proper recycling of the receptor. Our results identify a new role for PDZ-domain-mediated protein interactions and for the actin cytoskeleton in endocytic sorting, and suggest a mechanism by which GRK-mediated phosphorylation could regulate membrane trafficking of G-protein-coupled receptors after endocytosis.
authors.affiliation: Department of Biochemistry and Biophysics, University of California, San Francisco 94143, USA.
authors.forename: T T
authors.initials: TT
authors.lastname: Cao
authors.forename: H W
authors.initials: HW
authors.lastname: Deacon
authors.forename: D
authors.initials: D
authors.lastname: Reczek
authors.forename: A
authors.initials: A
authors.lastname: Bretscher
authors.forename: M
authors.initials: M
authors.lastname: von Zastrow
mesh_terms: D000199:Actins / Q000378:metabolism; D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D001665:Binding Sites; D019921:Biotinylation; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000494:pharmacology; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism*; D002460:Cell Line; D004705:Endocytosis / Q000187:drug effects / Q000502:physiology*; D011992:Endosomes / Q000378:metabolism*; D006801:Humans; D007545:Isoproterenol / Q000494:pharmacology; D008247:Lysosomes / Q000378:metabolism*; D008969:Molecular Sequence Data; D010750:Phosphoproteins / Q000737:chemistry / Q000378:metabolism*; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism; D018343:Receptors, Adrenergic, beta-2 / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D012694:Serine / Q000378:metabolism; D017923:Sodium-Hydrogen Exchangers; D013844:Thiazoles / Q000494:pharmacology; D053778:Thiazolidines
chemical_list: D000199:Actins; D000318:Adrenergic beta-Agonists; D019086:Bridged Bicyclo Compounds, Heterocyclic; D002352:Carrier Proteins; D010750:Phosphoproteins; D018343:Receptors, Adrenergic, beta-2; D011994:Recombinant Proteins; D017923:Sodium-Hydrogen Exchangers; D013844:Thiazoles; D053778:Thiazolidines; C093376:sodium-hydrogen exchanger regulatory factor; D012694:Serine; D020794:Receptor Protein-Tyrosine Kinases; D007545:Isoproterenol; C037068:latrunculin B