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A quantitative characterization of the yeast heterotrimeric G protein cycle

Yi, Tau-Mu and Kitano, Hiroaki and Simon, Melvin I. (2003) A quantitative characterization of the yeast heterotrimeric G protein cycle. Proceedings of the National Academy of Sciences of the United States of America, 100 (19). pp. 10764-10769. ISSN 0027-8424. PMCID PMC196877. doi:10.1073/pnas.1834247100.

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The yeast mating response is one of the best understood heterotrimeric G protein signaling pathways. Yet, most descriptions of this system have been qualitative. We have quantitatively characterized the heterotrimeric G protein cycle in yeast based on direct in vivo measurements. We used fluorescence resonance energy transfer to monitor the association state of cyan fluorescent protein (CFP)-Galpha and Gbetagamma-yellow fluorescent protein (YFP), and we found that receptor-mediated G protein activation produced a loss of fluorescence resonance energy transfer. Quantitative time course and dose-response data were obtained for both wild-type and mutant cells possessing an altered pheromone response. These results paint a quantitative portrait of how regulators such as Sst2p and the C-terminal tail of a-factor receptor modulate the kinetics and sensitivity of G protein signaling. We have explored critical features of the dynamics including the rapid rise and subsequent decline of active G proteins during the early response, and the relationship between the G protein activation dose-response curve and the downstream dose-response curves for cell-cycle arrest and transcriptional induction. Fitting the data to a mathematical model produced estimates of the in vivo rates of heterotrimeric G protein activation and deactivation in yeast.

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Additional Information:© 2003 by the National Academy of Sciences. Contributed by Melvin I. Simon, July 14, 2003. Published online before print September 5, 2003, 10.1073/pnas.1834247100 We thank Drs. Ray Deshaies and Chris Rao for critical reading of the manuscript; the Deshaies laboratory for yeast strains and vectors; and the Simon laboratory for valuable discussions. This work was supported by the Exploratory Research for Advanced Technology Kitano Symbiotic Systems Project of the Japanese Science and Technology Corporation.
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Japan Science and Technology AgencyUNSPECIFIED
Issue or Number:19
PubMed Central ID:PMC196877
Record Number:CaltechAUTHORS:YITpnas03
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:1111
Deposited By: Tony Diaz
Deposited On:20 Dec 2005
Last Modified:08 Nov 2021 19:07

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