FIG. 7.

Role of G proteins in filamentous growth and mating in budding and fission yeasts. In both yeasts, two Gα proteins regulate cellular responses to pheromone and nutrients. In both, one functions as a heterotrimeric G protein with a βγ partner, and the other signals in conjunction with Ras. Interestingly, the heterotrimeric G protein is coupled to pheromone receptors in S. cerevisiae but to the nutrient sensor in S. pombe. Importantly, the βγ subunits appear to function with only one of the two Gα subunits in both organisms. MAPK, MAP kinase; AC, adenylylcyclase.