Pdr1p binds to the promoter of RPN4 but not to that of FLR1 in the presence of selenite. The binding of Pdr1p to promoters was assessed by combining chromatin immunoprecipitation with real-time quantitative PCR, using strains harboring a chromosomal tagged version of Pdr1p (myc-Pdr1p). Sequence enrichment in the ChIP (i.e. ChIP/whole cell extract ratio) was normalized using the ACT1 ORF as a reference. Similar experiments were conducted on cells with the untagged Pdr1p as a negative control ("mock ChIP"). The PDR5 promoter was used as a positive control for Pdr1p binding. The results shown for FLR1 were obtained using a pair of oligonucleotides spanning the PDRE motif present in the FLR1 promoter. The cells were exposed to 1 mM of selenite (+) or mock-treated (-) for 60 minutes before the beginning of the ChIP procedure.