An α-mating-type-specific mutation causing specific defect in sexual agglutinability in the yeast Saccharomyces cerevisiae.

We have identified a recessive α-mating-type-specific gene agαl causing agglutinability defect without significant effects on other sexual activities. a cells carrying agαl showed sexual agglutination with α cells but α cells carrying agαl showed sexual agglutination with neither α cells nor a cells. α cells carrying agαl produced α pheromone and responded to a pheromone just like wild α cells. α cells carrying agαl showed a little decreased but significant mating ability when tested on solid media or membrane filter. The agαl mutant is different from any α-specific ste mutants found so far in many sexual activities. The agαl gene is recessive, and unlinked to the mating type locus. Biological significance of the α mating type agglutinability is discussed based on the results obtained with the mutant.