- mating-type genes
Genes that, in Saccharomyces cerevisiae, specify into which of the two mating types (a and a S a particular cell falls. Only unlike mating type haploids will fuse. The interest derives from the way in which mating type is switched: the existing gene is removed and a new gene, derived from a (silent) master copy elsewhere in the genome is spliced in. Later this gene will in its turn be replaced by a new copy of the old gene, also derived from a silent "master". The a- and a -genes code for pheromones that affect cells of the opposite mating type. Similar mating-type genes are known from other yeasts, and the switching mechanism (cassette mechanism) may be used more generally.
Dictionary of molecular biology. 2004.