Structural highlights
Function
[GBG1_BOVIN] Guanine nucleotide-binding proteins (G proteins) are involved as a modulator or transducer in various transmembrane signaling systems. The beta and gamma chains are required for the GTPase activity, for replacement of GDP by GTP, and for G protein-effector interaction.
Publication Abstract from PubMed
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 betagamma subunit complex, especially the C-terminal domain of the transducin gamma subunit, Gtgamma(60-71)farnesyl, plays a pivotal role in allosteric regulation of nucleotide exchange on the transducin alpha 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 gamma 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 betagamma complex in signal transfer to G proteins.
Rhodopsin controls a conformational switch on the transducin gamma subunit.,Kisselev OG, Downs MA Structure. 2003 Apr;11(4):367-73. PMID:12679015[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Kisselev OG, Downs MA. Rhodopsin controls a conformational switch on the transducin gamma subunit. Structure. 2003 Apr;11(4):367-73. PMID:12679015
