Enhancement of pheromone response by RGS9 and Gβ5 in yeast

Abstract

The G-protein γ-subunit-like (GGL) domain present within a subfamily of RGS proteins binds specifically to Gβ5. This interaction and resulting biological effect impacts the standard model of heterotrimeric G-protein signaling. It has been hypothesized that the RGS/Gβ5 may potentially substitute for Gβγ in the heterotrimeric complex. Saccharomyces cerevisiae pheromone responsive mating signaling pathway is primarily driven by Gβγ. We evaluated GGL containing RGS9 and RGS7 for functional complementation in a RGS (sst2Δ) knockout yeast strain. The potential of Gβ5 to augment the function of these RGS proteins was also evaluated. While Gβ5 had no effect on RGS7, coexpression of Gβ5 with RGS9 enhanced cell cycle arrest, suggesting that under certain conditions, RGS9 and Gβ5 may possibly function as βγ dimer. Furthermore, we demonstrate that Gβ5 can complement a ste4Δ, the yeast β-subunit, thus providing the first evidence of functional complementation of a mammalian Gβ. © 2004 Elsevier Inc. All rights reserved.