Controlled transcription of the yeast regulatory gene GAL80.

Transcription of the tightly linked genes GAL7-GAL10-GAL1 encoding three galactose-metabolizing enzymes in Saccharomyces cerevisiae is regulated by an interplay of the positive regulatory gene GAL4 and the negative regulatory gene GAL80. The concentration of GAL80 mRNA (determined by a quantitative blot hybridization) was nearly comparable to that of URA3 mRNA, in the wild-type yeast grown in medium with glucose or glycerol. The intracellular concentration of GAL80 mRNA increased by changing the carbon source to galactose by a factor of more than 5, in contrast to a GAL4 mRNA concentration which is essentially unaffected by galactose [Laughon and Gesteland, Proc. Natl. Acad. Sci. USA 79 (1982) 6827-6831]. The inducible expression of the GAL80 gene was suggested to involve its own product and also the product of GAL4 by using various mutations in those genes.