Affordable Access

Publisher Website

Rhodopsin Controls a Conformational Switch on the Transducin γ Subunit

Authors
Journal
Structure
0969-2126
Publisher
Elsevier
Publication Date
Volume
11
Issue
4
Identifiers
DOI: 10.1016/s0969-2126(03)00045-5
Keywords
  • Gtp Binding Protein
  • γ Subunit
  • G Protein-Coupled Receptor
  • Rhodopsin
  • Transducin
Disciplines
  • Biology

Abstract

Abstract Rhodopsin, a prototypical G protein-coupled receptor, catalyzes the activation of a heterotrimeric G protein, transducin, to initiate a visual signaling cascade in photoreceptor cells. The βγ subunit complex, especially the C-terminal domain of the transducin γ subunit, Gtγ(60–71)farnesyl, plays a pivotal role in allosteric regulation of nucleotide exchange on the transducin α subunit by light-activated rhodopsin. We report that this domain is unstructured in the presence of an inactive receptor but forms an amphipathic helix upon rhodopsin activation. A K65E/E66K charge reversal mutant of the γ subunit has diminished interactions with the receptor and fails to adopt the helical conformation. The identification of this conformational switch provides a mechanism for active GPCR utilization of the βγ complex in signal transfer to G proteins.

There are no comments yet on this publication. Be the first to share your thoughts.