Upstream activating sequence

An upstream activation sequence (UAS) is a cis-acting regulatory sequence. It is distinct from the promoter and increases the expression of a neighbouring gene. Its property to bind the GAL4 protein is utilised in the GAL4/UAS technique for controlled gene misexpression in Drosophila.

Instances
It has been shown to be involved in five of the seven genes which are glucose repressed. These genes were repressed in yeast (Saccharomyces cerevisiae) eventually after growing for hours in YPD (Yeast peptone dextrose) media. After using up glucose for fermentation, these genes get activated for aerobic respiration.

The Gal4 dimer binds to the UASs upstream of the various GAL genes (Cortes).