The SSL1 gene of S. cerevisiae which is involved in the cell-type specific recovery of mating type alpha cells from cell cycle arrest by the mating hormone a-factor has been cloned as a 1 kb Sau3A fragment in a complementing plasmid from a library of S. cerevisae genomic DNA. Disruption of this gene in wild-type alpha-cells results in the ssl1- phenotype which is characterized by an extreme sensitivity to a-factor. Transcription analysis revealed that the SSL1 gene is transcribed only in MAT alpha cells but not in MAT alpha or diploid (MAT alpha/MAT alpha) cells defining it as a member of the set of alpha-specific genes.