FIG. 6.

TBP occupancy at promoters in vivo. (A) Protein levels in cells expressing HA₃-tagged TBP derivatives as determined by Western blotting with antibodies to TBP (α-TBP) or HA-1 epitope (12CA5) (α-HA). Levels of HA₃-TBP and HA₃-TBP-ΔN69 were equalized by placing HA₃-TBP under the control of a copper-regulable promoter and growing cells at an appropriate concentration of copper. wt, wild types. (B) Chromatin immunoprecipitation. Strains containing the indicated HA₃-tagged TBP derivatives were treated with formaldehyde, and cross-linked protein-DNA complexes were immunoprecipitated with the 12CA5 monoclonal antibody to the HA-1 epitope. DNAs recovered from protein-DNA complexes prior to (Total) or after immunoprecipitation (IP) were analyzed by PCR with promoter-specific oligonucleotides. Units of TBP occupancy (40) are indicated under the corresponding panels and are relative to the value for the tRNA^CAA promoter in a strain containing HA₃-TBP, which was assigned a value of 100.