Dynamics of arrestin-rhodopsin interactions: Loop movement is involved in arrestin activation and receptor binding

Martha E. Sommer, David L. Farrens, J. Hugh McDowell, Lauren A. Weber, W. Clay Smith

Research output: Contribution to journalArticle

44 Scopus citations

Abstract

In this study we investigate conformational changes in Loop V-VI of visual arrestin during binding to light-activated, phosphorylated rhodopsin (Rho*-P) using a combination of site-specific cysteine mutagenesis and intramolecular fluorescence quenching. Introduction of cysteines at positions in the N-domain at residues predicted to be in close proximity to Ile-72 in Loop V-VI of arrestin (i.e. Glu-148 and Lys-298) appear to form an intramolecular disulfide bond with I72C, significantly diminishing the binding of arrestin to Rho*-P. Using a fluorescence approach, we show that the steady-state emission from a monobromobimane fluorophore in Loop V-VI is quenched by tryptophan residues placed at 148 or 298. This quenching is relieved upon binding of arrestin to Rho*-P. These results suggest that arrestin Loop V-VI moves during binding to Rho*-P and that conformational flexibility of this loop is essential for arrestin to adopt a high affinity binding state.

Original languageEnglish (US)
Pages (from-to)25560-25568
Number of pages9
JournalJournal of Biological Chemistry
Volume282
Issue number35
DOIs
StatePublished - Aug 31 2007

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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