SUMMARY PARAGRAPH for GAL80
GAL80 encodes a transcriptional repressor involved in transcriptional regulation in response to galactose (2). In conjunction with Gal4p and Gal3p, Gal80p coordinately regulates the expression of genes containing a GAL upstream activation site in their promoter (UAS-GAL), which includes the GAL metabolic genes GAL1, GAL10, GAL2, and GAL7 (reviewed in 3). Cells null for gal80 constitutively express GAL genes, even in non-inducing media (4).
In the absence of galactose, Gal80p binds, as a dimer, to the transcription factor Gal4p, thus preventing Gal4p from recruiting other factors of the Pol II transcription machinery (5). In the presence of galactose,Gal3p interacts with Gal80p, which relieves inhibition of Gal4p and results in GAL gene expression (6). Gal80p interacts with Gal3p as a monomer and only in the presence of both galactose and ATP (2). In the absence of Gal3p, the Gal1p galactokinase can interact with and partially inhibit Gal80p function (2, 7).
GAL80 transcription is also regulated by the Gal3p/Gal80p/Gal4p feedback mechanism that regulates the other GAL genes. However, unlike expression of the GAL structural genes, which is tightly controlled because of the presence of multiple UAS-GALs in their promoters, GAL80 has high basal levels of transcription due to the presence of only a single UAS-GAL in its promoter (8).
Last updated: 2013-05-23