Figure 4.

Model for repression by Rme1p. In the absence of Rme1p, the activator Hap1p can bind to UAS1 and activate transcription (Upper). When Rme1p is present, it binds to upstream sites and alters the template to prevent activator binding (Lower). Repression and activator exclusion depend upon sequences flanking Rme1p binding sites, which may include binding sites for a hypothetical corepressor (designated CoR). Activator exclusion also depends upon Rgr1p and Sin4p, and may result from an altered state of chromatin (depicted by shaded circles).