The sexual agglutination substance is secreted through the yeast secretory pathway in Saccharomyces cerevisiae

Abstract

A Saccharomyces cerevisiae a strain carrying the secretory mutation sec1, sec7 or sec18 showed no sexual agglutination ability when treated with α pheromone at the restrictive temperature 36° C, although the a agglutination substance had accumulated in the cytoplasm. These cells became sexually agglutinable, with a concomitant decrease in the agglutination substance in the cytoplasm, when the temperature was shifted from 36° C down to the permissive temperature 24° C after the addition of, cycloheximide. The a agglutination substance was barely detectable in sec53 cells (a) treated with α pheromone at 36° C, indicating that the active a agglutination substance was formed after the export of its precursor into the endoplasmic reticulum. These results indicate that the a agglutination substance is exported through the yeast secretory pathway and that α pheromone acts at the level of synthesis of the precursor molecule of the substance. An α strain carrying sec1, sec7 or sec18 behaved just like an a strain carrying the sec gene in the induction of agglutination ability by the opposite mating type sex pheromone.