title: Structures of rhodopsin kinase in different ligand states reveal key elements involved in G protein-coupled receptor kinase activation.
abstract: G protein-coupled receptor (GPCR) kinases (GRKs) phosphorylate activated heptahelical receptors, leading to their uncoupling from G proteins. Here we report six crystal structures of rhodopsin kinase (GRK1), revealing not only three distinct nucleotide-binding states of a GRK but also two key structural elements believed to be involved in the recognition of activated GPCRs. The first is the C-terminal extension of the kinase domain, which was observed in all nucleotide-bound GRK1 structures. The second is residues 5-30 of the N terminus, observed in one of the GRK1.(Mg2+)2.ATP structures. The N terminus was also clearly phosphorylated, leading to the identification of two novel phosphorylation sites by mass spectral analysis. Co-localization of the N terminus and the C-terminal extension near the hinge of the kinase domain suggests that activated GPCRs stimulate kinase activity by binding to this region to facilitate full closure of the kinase domain.
authors.affiliation: Life Sciences Institute, Department of Pharmacology, University of Michigan, Ann Arbor, Michigan 48109-2216, USA.
authors.forename: Puja
authors.initials: P
authors.lastname: Singh
authors.forename: Benlian
authors.initials: B
authors.lastname: Wang
authors.forename: Tadao
authors.initials: T
authors.lastname: Maeda
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Palczewski
authors.forename: John J G
authors.initials: JJ
authors.lastname: Tesmer
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002417:Cattle; D004789:Enzyme Activation; D051606:G-Protein-Coupled Receptor Kinase 1 / Q000737:chemistry* / Q000502:physiology*; D007700:Kinetics; D008024:Ligands; D008954:Models, Biological; D008968:Molecular Conformation; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid
chemical_list: D008024:Ligands; D043562:Receptors, G-Protein-Coupled; D051606:G-Protein-Coupled Receptor Kinase 1