The Transitory Complexes Between Photoexcited Rhodopsin and Transducin. Biochemical and Spectroscopic Studies

  • F. Bornancin
  • C. Pfister
Conference paper
Part of the Research Reports in Physics book series (RESREPORTS)

Abstract

In the first step of the visual transduction cascade, photoexcited rhodopsin (R*ret) binds to a GDP-carrying transducin (TGDP), allowing the release of the GDP from its site on T. We obtained a R*ret-Te complex (ret for retinal present, e for nucleotide site empty), undissociable almost indefinitely in a medium with physiological ionic strength. In this complex, rhodopsin is totally locked in the Meta-II conformation (R*ret). Incubation in a low ionic strength medium partially dissociates Te (probably a denatured form of transducin). In the presence of GDP, a R*ret-TGDP complex is obtained. TGDP appears to have a high binding affinity to R*ret in physiological ionic conditions. We show that the binding of Te or TGDP on cytoplasmic loops of rhodopsin induces different retroactions on the retinal site in rhodopsin.

Keywords

Sedimentation Trypsin Turbidity Hepes Bleached 

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Copyright information

© Springer-Verlag Berlin Heidelberg 1992

Authors and Affiliations

  • F. Bornancin
    • 1
  • C. Pfister
    • 1
  1. 1.Laboratoire de Biophysique Moléculaire et CellulaireCEN-Grenoble, 85XGrenobleFrance

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