Mating reaction in Saccharomyces cerevisiae. VII. Effect of proteolytic enzymes on sexual agglutinability and isolation of crude sex-specific substances responsible for sexual agglutination.

The effect of proteolytic enzymes on sexual agglutinability of haploid cells of the yeast Saccharomyces cerevisiae was examined. Sexual agglutinability of cells of both a and alpha types was lost on treatment with alkaline protease and two kinds of neutral proteases of Bacillus subtilis, pronase and alpha-chymotrypsin. Agglutinability of alpha type cells was lost after treatment with acid protease of Rhizopus chinensis and trypsin, but that of a type cells was not. These results indicate that the sex-specific substance responsible for the sexual agglutination (agglutination factor) in a type cells differ from that in alpha type cells. Agglutination factors were solubilized from cell-wall fractions of both mating types by Glusalase treatment. These crude factors specifically inhibited the agglutinability of cells of the opposite mating type with little effect on the agglutinability of cells of the same mating type.