|Journal of Structural Biology (2011) 176:387-394|
|Transcontinental EM Initiative for Membrane Proteins|
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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.
|chemistry ultrastructure |
|Models, Molecular Protein Binding Multiprotein Complexes Guanosine Triphosphate Light Electrophoresis, Polyacrylamide Gel Microscopy, Electron, Transmission Protein Multimerization Rhodopsin Guanosine Diphosphate Transducin |
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