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XB-ART-38245
J Biol Chem 2008 Oct 31;28344:30015-24. doi: 10.1074/jbc.M803953200.
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Activation-dependent hindrance of photoreceptor G protein diffusion by lipid microdomains.

Wang Q , Zhang X , Zhang L , He F , Zhang G , Jamrich M , Wensel TG .


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The dynamics of G protein-mediated signal transduction depend on the two-dimensional diffusion of membrane-bound G proteins and receptors, which has been suggested to be rate-limiting for vertebrate phototransduction, a highly amplified G protein-coupled signaling pathway. Using fluorescence recovery after photobleaching (FRAP), we measured the diffusion of the G protein transducin alpha-subunit (Galpha(t)) and the G protein-coupled receptor rhodopsin on disk membranes of living rod photoreceptors from transgenic Xenopus laevis. Treatment with either methyl-beta-cyclodextrin or filipin III to disrupt cholesterol-containing lipid microdomains dramatically accelerated diffusion of Galpha(t) in its GTP-bound state and of the rhodopsin-Galphabetagamma(t) complex but not of rhodopsin or inactive GDP-bound Galphabetagamma. These results imply an activity-dependent sequestration of G proteins into cholesterol-dependent lipid microdomains, which limits diffusion and exclude the majority of free rhodopsin and the free G protein heterotrimer. Our data offer a novel demonstration of lipid microdomains in the internal membranes of living sensory neurons.

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Species referenced: Xenopus laevis
Genes referenced: gnat1 gnaz mtor rho suclg1

References [+] :
Adamus, Anti-rhodopsin monoclonal antibodies of defined specificity: characterization and application. 1991, Pubmed