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. 1999 Oct 15;18(20):5577–5591. doi: 10.1093/emboj/18.20.5577

A novel regulator of G protein signalling in yeast, Rgs2, downregulates glucose-activation of the cAMP pathway through direct inhibition of Gpa2.

M Versele 1, J H de Winde 1, J M Thevelein 1
PMCID: PMC1171626  PMID: 10523302

Abstract

We have characterized a novel member of the recently identified family of regulators of heterotrimeric G protein signalling (RGS) in the yeast Saccharomyces cerevisiae. The YOR107w/RGS2 gene was isolated as a multi-copy suppressor of glucose-induced loss of heat resistance in stationary phase cells. The N-terminal half of the Rgs2 protein consists of a typical RGS domain. Deletion and overexpression of Rgs2, respectively, enhances and reduces glucose-induced accumulation of cAMP. Overexpression of RGS2 generates phenotypes consistent with low activity of cAMP-dependent protein kinase A (PKA), such as enhanced accumulation of trehalose and glycogen, enhanced heat resistance and elevated expression of STRE-controlled genes. Deletion of RGS2 causes opposite phenotypes. We demonstrate that Rgs2 functions as a negative regulator of glucose-induced cAMP signalling through direct GTPase activation of the Gs-alpha protein Gpa2. Rgs2 and Gpa2 constitute the second cognate RGS-G-alpha protein pair identified in yeast, in addition to the mating pheromone pathway regulators Sst2 and Gpa1. Moreover, Rgs2 and Sst2 exert specific, non-overlapping functions, and deletion mutants in Rgs2 and Sst2 are complemented to some extent by different mammalian RGS proteins.

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