Influence of carbon catabolite repression on the G1 arrest of Saccharomyces cerevisiae MATa cells by alpha factor.

Cells of the yeast Saccharomyces cerevisiae of the a mating type were arrested at the G1 phase of the cell division cycle after treatment with alpha factor in a culture medium containing a high concentration (2%, w/v, or higher) of a catabolite-repressing sugar. In media containing either a lower concentration of sugar or a non-fermentable carbon source, the extent of G1 arrest induced by the pheromone was reduced or became undetectable. Under catabolite-derepressing conditions alpha factor was inactivated by a cells at a higher rate than that found in repressing media. These results indicate the existence of a close correlation between the action of alpha factor on a cells and conditions of catabolite repression or derepression. A joint mechanism of action of alpha factor and catabolite-repressing carbon sources on a cells is postulated.