The solution structure and activation of visual arrestin studied by small-angle X-ray scattering

Eur J Biochem. 2002 Aug;269(15):3801-9. doi: 10.1046/j.1432-1033.2002.03071.x.


Visual arrestin is converted from a 'basal' state to an 'activated' state by interaction with the phosphorylated C-terminus of photoactivated rhodopsin (R*), but the conformational changes in arrestin that lead to activation are unknown. Small-angle X-ray scattering (SAXS) was used to investigate the solution structure of arrestin and characterize changes attendant upon activation. Wild-type arrestin forms dimers with a dissociation constant of 60 micro m. Small conformational changes, consistent with local movements of loops or the mobile N- or C-termini of arrestin, were observed in the presence of a phosphopeptide corresponding to the C-terminus of rhodopsin, and with an R175Q mutant. Because both the phosphopeptide and the R175Q mutation promote binding to unphosphorylated R*, we conclude that arrestin is activated by subtle conformational changes. Most of the arrestin will be in a dimeric state in vivo. Using the arrestin structure as a guide [Hirsch, J.A., Schubert, C., Gurevich, V.V. & Sigler, P.B. (1999) Cell 97, 257-269], we have identified a model for the arrestin dimer that is consistent with our SAXS data. In this model, dimerization is mediated by the C-terminal domain of arrestin, leaving the N-terminal domains free for interaction with phosphorylated R*.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Arrestin / chemistry*
  • Arrestin / genetics
  • Arrestin / metabolism
  • Dimerization
  • Models, Molecular
  • Molecular Sequence Data
  • Mutation
  • Peptide Fragments / chemistry
  • Peptide Fragments / metabolism
  • Phosphoproteins / chemistry
  • Phosphoproteins / metabolism
  • Phosphorylation
  • Protein Conformation
  • Rhodopsin / chemistry
  • Rhodopsin / genetics
  • Rhodopsin / metabolism
  • Scattering, Radiation
  • Solutions
  • X-Rays


  • Arrestin
  • Peptide Fragments
  • Phosphoproteins
  • Solutions
  • Rhodopsin