PROTEIN DEGRADATION, MEIOSIS AND SPORULATION IN PROTEINASE-DEFICIENT MUTANTS OF SACCHAROMYCES CEREVISIAE

[摘要] During the process of sporulation, a /α diploids degrade about 50% of their vegetative proteins. This degradation is not sporulation specific, for asporogenous diploids of a / a mating type degrade their vegetative proteins in a fashion similar to that of their a /α counterparts. Diploids lacking carboxypeptidase Y activity, prc1/prc1 , show about 80% of wild-type levels of protein degradation, but are unimpaired in the production of normal asci. Diploids lacking proteinase B activity, prb1/prb1 , show about 50% of wild-type levels of protein degradation. The effect on degradation of the proteinase B deficiency is epistatic to the degradation deficit attributable to the carboxypeptidase Y deficiency. The prb1 homozygotes undergo meiosis and produce spores, but the asci and, possibly, the spores are abnormal. Diploids homozygous for the pleiotropic pep4-3 mutation show only 30% of the wild-type levels of degradation when exposed to a sporulation regimen, and do not undergo meiosis or sporulation. Neither proteinase B nor carboxypeptidase Y is necessary for germination of spores. ——Approximately half of the colonies arising from a / a or α/α diploids exposed to the sporulation regiment that express an initially heterozygous drug-resistance marker ( can1 ) appear to arise from mating-type switches followed by meiosis and sporulation.

[学科分类] 医学（综合）