An α-specific gene, SAG1 is required for sexual agglutination in Saccharomyces cerevisiae

Summary

Seven α-specific mutants specifically defective in sexual agglutinability were isolated. The other α mating functions exhibited by these mutants, designated sag mutants, such as the production of α pheromone and response to a mating pheromone, were normal. While the MATα sag1 cells did not agglutinate with wild-type a cells, the MATα sag1 cells did, indicating that the SAG1 gene is expressed only in α cells. The mutations were semi-dominant and fell into a single complementation group, SAG1, which was mapped near met3 on chromosome X. Complementation analysis showed that sag1 and aga1, the latter being a previously reported α-specific mutation, were mutations in the same gene.