期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1976
卷号：73
期号：6
页码：2061-2065
DOI：10.1073/pnas.73.6.2061
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要："Killer" strains of Saccharomyces cerevisiae are those that harbor a double-stranded RNA plasmid and secrete a toxin that kills only strains not carrying this plasmid (sensitives). Two chromosomal genes (kex1 and kex2) are required for the secretion of toxin by plasmid-carrying strains. The kex2 gene, which maps at a site distinct from the mating-type locus, is also required for normal mating by alpha strains and meiotic sporulation in all strains. Strains that are alpha mating-type and kex2 fail to secrete the pheromone alpha-factor or to respond to the alpha-factor II pheromone which causes a morphological change, but they do respond to alpha-factor I which causes G1 arrest in alpha cells. Strains that are alpha mating-type and kex2 show no defect in mating; pheromone secretion, or response to alpha-factor. Diploids that are homozygous for the kex2 mutation, unlike wildtype or heterozygous diploids, fail to undergo sporulation, with the defect occurring in the final spore maturation stage. These same defects in the sexual cycle are present in all kex2 mutants independent of the presence of the "killer" plasmid.
