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Role of Monomer/Tetramer Equilibrium of Rod Visual Arrestin in the Interaction with Phosphorylated Rhodopsin.
Imamoto, Yasushi; Kojima, Keiichi; Maeda, Ryo; Shichida, Yoshinori; Oka, Toshihiko.
Afiliação
  • Imamoto Y; Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.
  • Kojima K; Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.
  • Maeda R; Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.
  • Shichida Y; Research Organization for Science and Technology, Ritsumeikan University, Kusatsu 525-8577, Japan.
  • Oka T; Department of Physics, Faculty of Science, Shizuoka University, Shizuoka 422-8529, Japan.
Int J Mol Sci ; 24(5)2023 Mar 04.
Article em En | MEDLINE | ID: mdl-36902393
The phototransduction cascade in vertebrate rod visual cells is initiated by the photoactivation of rhodopsin, which enables the activation of the visual G protein transducin. It is terminated by the phosphorylation of rhodopsin, followed by the binding of arrestin. Here we measured the solution X-ray scattering of nanodiscs containing rhodopsin in the presence of rod arrestin to directly observe the formation of the rhodopsin/arrestin complex. Although arrestin self-associates to form a tetramer at physiological concentrations, it was found that arrestin binds to phosphorylated and photoactivated rhodopsin at 1:1 stoichiometry. In contrast, no complex formation was observed for unphosphorylated rhodopsin upon photoactivation, even at physiological arrestin concentrations, suggesting that the constitutive activity of rod arrestin is sufficiently low. UV-visible spectroscopy demonstrated that the rate of the formation of the rhodopsin/arrestin complex well correlates with the concentration of arrestin monomer rather than the tetramer. These findings indicate that arrestin monomer, whose concentration is almost constant due to the equilibrium with the tetramer, binds to phosphorylated rhodopsin. The arrestin tetramer would act as a reservoir of monomer to compensate for the large changes in arrestin concentration in rod cells caused by intense light or adaptation.
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Texto completo: 1 Base de dados: MEDLINE Assunto principal: Rodopsina / Células Fotorreceptoras Retinianas Bastonetes Idioma: En Revista: Int J Mol Sci Ano de publicação: 2023 Tipo de documento: Article País de afiliação: Japão

Texto completo: 1 Base de dados: MEDLINE Assunto principal: Rodopsina / Células Fotorreceptoras Retinianas Bastonetes Idioma: En Revista: Int J Mol Sci Ano de publicação: 2023 Tipo de documento: Article País de afiliação: Japão