Fig. 6. Acetylation augments binding of TAF_I68 to the rDNA promoter. (A) TAF_I68 binds specifically to the rDNA promoter. A 300 ng aliquot of recombinant FLAG-TAF_I68 was incubated with 5 fmol of radiolabeled rDNA probe, and DNA–protein complexes were analyzed by electrophoresis on 5% native polyacrylamide gels. For competition, reactions were supplemented with 250, 500 and 1000 fmol, respectively, of an unlabeled fragment harboring sequences of either the rDNA promoter (lanes 3–5) or the rDNA terminator (lanes 6–8). (B) Binding of TAF_I68 to the rDNA promoter is enhanced by acetylation. Increasing amounts (50–150 ng) of FLAG-TAF_I68 were acetylated with PCAF, hGCN5 and CBP, respectively, and assayed for DNA binding by EMSA. In lanes 1–3, the reactions contained FLAG-TAF_I68 alone.