title: G Protein-coupled Receptor Kinases of the GRK4 Protein Subfamily Phosphorylate Inactive G Protein-coupled Receptors (GPCRs).
abstract: G protein-coupled receptor (GPCR) kinases (GRKs) play a key role in homologous desensitization of GPCRs. It is widely assumed that most GRKs selectively phosphorylate only active GPCRs. Here, we show that although this seems to be the case for the GRK2/3 subfamily, GRK5/6 effectively phosphorylate inactive forms of several GPCRs, including β2-adrenergic and M2 muscarinic receptors, which are commonly used as representative models for GPCRs. Agonist-independent GPCR phosphorylation cannot be explained by constitutive activity of the receptor or membrane association of the GRK, suggesting that it is an inherent ability of GRK5/6. Importantly, phosphorylation of the inactive β2-adrenergic receptor enhanced its interactions with arrestins. Arrestin-3 was able to discriminate between phosphorylation of the same receptor by GRK2 and GRK5, demonstrating preference for the latter. Arrestin recruitment to inactive phosphorylated GPCRs suggests that not only agonist activation but also the complement of GRKs in the cell regulate formation of the arrestin-receptor complex and thereby G protein-independent signaling.
authors.affiliation: From the Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232.
authors.forename: Lingyong
authors.initials: L
authors.lastname: Li
authors.affiliation: the Life Sciences Institute, University of Michigan, Ann Arbor, Michigan 48109-2216, and.
authors.forename: Kristoff T
authors.initials: KT
authors.lastname: Homan
authors.affiliation: From the Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232.
authors.forename: Sergey A
authors.initials: SA
authors.lastname: Vishnivetskiy
authors.affiliation: the Department of Molecular and Cellular Physiology, Stanford University, Stanford, California 94305.
authors.forename: Aashish
authors.initials: A
authors.lastname: Manglik
authors.affiliation: the Life Sciences Institute, University of Michigan, Ann Arbor, Michigan 48109-2216, and.
authors.forename: John J G
authors.initials: JJ
authors.lastname: Tesmer
authors.affiliation: From the Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232.
authors.forename: Vsevolod V
authors.initials: VV
authors.lastname: Gurevich
authors.affiliation: From the Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232, Eugenia.Gurevich@vanderbilt.edu.
authors.forename: Eugenia V
authors.initials: EV
authors.lastname: Gurevich
mesh_terms: D000818:Animals; D019390:Arrestins / Q000378:metabolism; D002417:Cattle; D054771:G-Protein-Coupled Receptor Kinase 4 / Q000235:genetics / Q000378:metabolism*; D054768:G-Protein-Coupled Receptor Kinases / Q000235:genetics / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D016297:Mutagenesis, Site-Directed; D010766:Phosphorylation; D043562:Receptors, G-Protein-Coupled / Q000819:agonists / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D019390:Arrestins; D043562:Receptors, G-Protein-Coupled; D011994:Recombinant Proteins; D054771:G-Protein-Coupled Receptor Kinase 4; D054768:G-Protein-Coupled Receptor Kinases
keywords: Activation; Adrenergic Receptor; Arrestin; G Protein-coupled Receptor (GPCR); G Protein-coupled Receptor Kinase; Phosphorylation; Rhodopsin