Genetic analysis of ras homologs in yeasts.

Ras proteins with extensive structural homology to mammalian p21ras have been studied in the two yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe. Comparative analysis of these two yeasts has revealed significant differences in the biochemical and physiological functions that are controlled by this subgroup of eukaryotic GTP-binding regulatory proteins. Despite such divergence of cellular functions, proteins and mechanisms involved in the regulation and modification of Ras proteins are highly conserved in yeasts and other eukaryotes. Genetic analysis of the function of yeast proteins that regulate or modify Ras proteins has provided important information about Ras proteins in general.