Transcriptional activator proteins bind to UAS elements in yeast

The Gal4 protein activates target genes through upstream-activating-sequence (UAS) elements. The Gal4 protein has two functional domains: a DNA-binding domain (pink square) and an activation domain (orange oval). The protein binds as a dimer to specific sequences upstream of the promoters of Gal-pathway genes. Some of the GAL genes are adjacent (GAL1, GAL10), whereas others are on different chromosomes. The GAL1 UAS element contains four Gal4-binding sites.