title: The G protein-coupled receptor kinase 2 is a microtubule-associated protein kinase that phosphorylates tubulin.
abstract: The G protein-coupled receptor kinase 2 (GRK2) is a serine/threonine kinase that phosphorylates and desensitizes agonist-occupied G protein-coupled receptors (GPCRs). Here we demonstrate that GRK2 is a microtubule-associated protein and identify tubulin as a novel GRK2 substrate. GRK2 is associated with microtubules purified from bovine brain, forms a complex with tubulin in cell extracts, and colocalizes with tubulin in living cells. Furthermore, an endogenous tubulin kinase activity that copurifies with microtubules has properties similar to GRK2 and is inhibited by anti-GRK2 monoclonal antibodies. Indeed, GRK2 phosphorylates tubulin in vitro with kinetic parameters very similar to those for phosphorylation of the agonist-occupied beta2-adrenergic receptor, suggesting a functionally relevant role for this phosphorylation event. In a cellular environment, agonist occupancy of GPCRs, which leads to recruitment of GRK2 to the plasma membrane and its subsequent activation, promotes GRK2-tubulin complex formation and tubulin phosphorylation. These findings suggest a novel role for GRK2 as a GPCR signal transducer mediating the effects of GPCR activation on the cytoskeleton.
authors.affiliation: Howard Hughes Medical Institute Laboratories and Departments of Medicine and Biochemistry, Duke University Medical Center, Durham, North Carolina 27710, USA.
authors.forename: J A
authors.initials: JA
authors.lastname: Pitcher
authors.forename: R A
authors.initials: RA
authors.lastname: Hall
authors.forename: Y
authors.initials: Y
authors.lastname: Daaka
authors.forename: J
authors.initials: J
authors.lastname: Zhang
authors.forename: S S
authors.initials: SS
authors.lastname: Ferguson
authors.forename: S
authors.initials: S
authors.lastname: Hester
authors.forename: S
authors.initials: S
authors.lastname: Miller
authors.forename: M G
authors.initials: MG
authors.lastname: Caron
authors.forename: R J
authors.initials: RJ
authors.lastname: Lefkowitz
authors.forename: L S
authors.initials: LS
authors.lastname: Barak
mesh_terms: D000818:Animals; D002417:Cattle; D002460:Cell Line; D017868:Cyclic AMP-Dependent Protein Kinases / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D016253:Microscopy, Immunoelectron; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000819:agonists; D014404:Tubulin / Q000378:metabolism*; D051552:beta-Adrenergic Receptor Kinases
chemical_list: D008869:Microtubule-Associated Proteins; D011956:Receptors, Cell Surface; D014404:Tubulin; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; D051552:beta-Adrenergic Receptor Kinases