FIG. 5.

Bur1 is associated with transcription elongation complexes in vivo. (A) HA₃-tagged Bur1 (YSB770) and Bur2 (YSB813) strains were analyzed using ChIPs as described in Materials and Methods. Locations of the PMA1 primers for PCR are depicted schematically. The number within the rectangle gives the size of the ORF in base pairs. The upper panel is the input used to normalize the PCR amplification. Samples were immunoprecipitated with anti-TBP, monoclonal antibody 12CA5 recognizing the HA-tagged Bur1 (left column) or Bur2 (right column), or anti-CTD (8WG16). The asterisk marks a nontranscribed PCR fragment included in all reactions as a background control. (B) ChIPs were carried out on several galactose-inducible genes to examine de novo recruitment of transcription complexes. Cells were grown in 2% raffinose and then switched to 2% glucose (GLU) or 2% galactose (GAL) for 4 h before formaldehyde cross-linking and ChIP analysis. Immunoprecipitations were done with anti-TBP and anti-HA antibodies recognizing the tagged Bur1 protein. Primers amplified the constitutive ADH1 promoter (Adh1p) or coding sequence (cds) or the corresponding locations within the indicated GAL genes.