Interaction of super-repressible and dominant constitutive mutations for the synthesis of galactose pathway enzymes in Saccharomyces cerevisiae

Mol Gen Genet. 1977 Apr 29;152(3):137-44. doi: 10.1007/BF00268810.


Two dominant uninducible mutant alleles in the gal80 locus were identified. The GAL80s-1 and GAL80s-2 mutants showed novel phenotypes in response to the newly isolated GAL81-1 mutant allele, a dominant constitutive mutation linked to the gal4 locus; the GAL80s-1 GAL81-1 strain was inducible and the GAL80s-2 GAL81-1 strain was uninducible. Many galactose positive revertants from the GAL80s-2 GAL81-1 strain were isolated. It was proved that each revertant was due to a secondary mutation either in the gal80 or GAL81 locus, whereas revertants due to mutation at the supposed controlling site for the structural gene cluster of the galactose-pathway enzymes have not been isolated.

MeSH terms

  • Carboxy-Lyases / metabolism
  • Galactose / metabolism*
  • Genes
  • Genes, Dominant
  • Genes, Regulator*
  • Genotype
  • Mutation
  • Phenotype
  • Saccharomyces cerevisiae / enzymology*


  • Carboxy-Lyases
  • Galactose