Journal article
Probing the mechanism of rhodopsin-catalyzed transducin activation
Journal of neurochemistry, Vol.77(1), pp.202-210
04/2001
DOI: 10.1046/j.1471-4159.2001.t01-1-00221.x
PMID: 11279276
Abstract
An agonist-bound G protein-coupled receptor (GPCR) induces a GDP/GTP exchange on the G protein alpha-subunit (G alpha) followed by the release of G alpha GTP and G beta gamma which, subsequently, activate their targets. The C-terminal regions of G alpha subunits constitute a major receptor recognition domain. In this study, we tested the hypothesis that the GPCR-induced conformational change is communicated from the G alpha C-terminus, via the alpha 5 helix, to the nucleotide-binding beta 6/alpha 5 loop causing GDP release. Mutants of the visual G protein, transducin, with a modified junction of the C-terminus were generated and analyzed for interaction with photoexcited rhodopsin (R*). A flexible linker composed of five glycine residues or a rigid three-turn alpha-helical segment was inserted between the 11 C-terminal residues and the alpha 5 helix of G alpha(t)-like chimeric G alpha, G alpha(ti). The mutant G alpha subunits with the Gly-loop (G alpha(ti)L) and the extended alpha 5 helix (G alpha(ti)H) retained intact interactions with G beta gamma(t), and displayed modestly reduced binding to R*. G alpha(ti)H was capable of efficient activation by R*. In contrast, R* failed to activate G alpha(ti)L, suggesting that the Gly-loop absorbs a conformational change at the C-terminus and blocks G protein activation. Our results provide evidence for the role of G alpha C-terminus/alpha 5 helix/beta 6/alpha 5 loop route as a dominant channel for transmission of the GPCR-induced conformational change leading to G protein activation.
Details
- Title: Subtitle
- Probing the mechanism of rhodopsin-catalyzed transducin activation
- Creators
- Michael NatochinMustapha MoussaifNikolai O Artemyev
- Resource Type
- Journal article
- Publication Details
- Journal of neurochemistry, Vol.77(1), pp.202-210
- DOI
- 10.1046/j.1471-4159.2001.t01-1-00221.x
- PMID
- 11279276
- ISSN
- 0022-3042
- eISSN
- 1471-4159
- Language
- English
- Date published
- 04/2001
- Academic Unit
- Molecular Physiology and Biophysics; Iowa Neuroscience Institute; Ophthalmology and Visual Sciences
- Record Identifier
- 9984070619502771
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