Rvb1 and Rvb2 are two highly conserved proteins in eukaryotes. They are involved in a large number of cellular processes and are essential for growth and viability. They associate with several different protein complexes and show a great variability of functions both when working together and separately. Despite their biological importance little is known about how these proteins carry out their functions, especially in regulation of transcription. Another highly conserved protein complex, the proteasome 19S regulatory particle has also been shown to be involved in transcriptional regulation at the yeast GAL1-10 promoter. Evidence presented here indicates co-operation between the Rpt1 and Rpt6 components of the 19S regulatory particle and the Rvb2 protein at GAL promoters in Saccharomyces cerevisiae.

Experiments were performed using N-degron tagged Rvb2 protein in order to determine if the Rvb2 protein is necessary for the localization of the Rpts to the GAL genes. Chromatin immunoprecipitation (ChIP) was performed before and after galactose induction and after Rvb2p degradation. Results show a direct requirement of the Rvb2 protein for transcription of both GAL1 and GAL10 and interestingly, after the Rvb2p degradation the association of the Rpt1 and Rpt6 to the GAL1/10 genes is lost. In addition, we also show that the association of the Rpt1 and Rpt6 to the GAL1/10 genes is within the gene regions but not at the UAS regions as previously thought.