Irregular Transpositions of Mating-type Genes in Yeast
This extract was created in the absence of an abstract.
Excerpt
Cell type in Saccharomyces is controlled by the MATa and MATα alleles of the mating-type locus (Lindegren and Lindegren 1943). These two alleles differ by a DNA substitution; ~650 bp are unique to MATa and ~750 bp are unique to MATα. Changes of cell type, for example, from a to α, reflect the substitution of a copy of an unexpressed α gene for the MATa allele. Changes from a to α and α to a are rare in yeast strains carrying the ho allele (heterothallic yeast) but can occur as often as every generation in yeast carrying the HO allele (homothallic yeast). The unexpressed donor loci (HML and HMR) for the transposition-substitution reaction have been identified by their hybridization to cloned MAT DNA. Thus, yeast can change cell type from α to a by the substitution of a replica of HMRa for the MATα allele and a to a by...
