title: Rhodopsin-transducin heteropentamer: three-dimensional structure and biochemical characterization.
abstract: The process of vision is initiated when the G protein-coupled receptor, rhodopsin (Rho), absorbs a photon and transitions to its activated Rho(∗) form. Rho(∗) binds the heterotrimeric G protein, transducin (G(t)) inducing GDP to GTP exchange and G(t) dissociation. Using nucleotide depletion and affinity chromatography, we trapped and purified the resulting nucleotide-free Rho(∗)·G(t) complex. Quantitative SDS-PAGE suggested a 2:1 molar ratio of Rho(∗) to G(t) in the complex and its mass determined by scanning transmission electron microscopy was 221±12kDa. A 21.6Å structure was calculated from projections of negatively stained Rho(∗)·G(t) complexes. The molecular envelope thus determined accommodated two Rho molecules together with one G(t) heterotrimer, corroborating the heteropentameric structure of the Rho(∗)·G(t) complex.
authors.affiliation: Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, OH 44106-4965, USA. bxj27@case.edu
authors.forename: Beata
authors.initials: B
authors.lastname: Jastrzebska
authors.forename: Philippe
authors.initials: P
authors.lastname: Ringler
authors.forename: David T
authors.initials: DT
authors.lastname: Lodowski
authors.forename: Vera
authors.initials: V
authors.lastname: Moiseenkova-Bell
authors.forename: Marcin
authors.initials: M
authors.lastname: Golczak
authors.forename: Shirley A
authors.initials: SA
authors.lastname: Müller
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Palczewski
authors.forename: Andreas
authors.initials: A
authors.lastname: Engel
mesh_terms: D004591:Electrophoresis, Polyacrylamide Gel; D006153:Guanosine Diphosphate / Q000737:chemistry; D006160:Guanosine Triphosphate / Q000737:chemistry; D008027:Light; D046529:Microscopy, Electron, Transmission; D008958:Models, Molecular; D046912:Multiprotein Complexes / Q000737:chemistry* / Q000648:ultrastructure; D011485:Protein Binding; D055503:Protein Multimerization; D012243:Rhodopsin / Q000737:chemistry* / Q000648:ultrastructure; D015293:Transducin / Q000737:chemistry* / Q000648:ultrastructure
chemical_list: D046912:Multiprotein Complexes; D006153:Guanosine Diphosphate; D006160:Guanosine Triphosphate; D012243:Rhodopsin; D015293:Transducin