PCAF interacts with CSB and Pol I.

<p>A. PCAF interacts with CSB and Pol I <i>in vivo</i>. Nuclear extracts from 293T cells were incubated with control IgGs, anti-CSB or anti-PCAF antibodies. About 10% of input and 80% of precipitated proteins were analyzed on western blots. B. CSB, PCAF and Pol I co-localize in nucleoli. Indirect immunofluorescence shows the localization of CSB, PCAF and Pol I in U2OS cells. Scale bar, 5 µm. C. CSB and PCAF are associated with rDNA. Cross-linked chromatins from NIH 3T3 cells were incubated with antibodies against IgG, Pol I (RPA194), TTF-1, CSB and PCAF. The precipitated DNA was analyzed by qRT-PCR using primer pairs that amplify the indicated regions in mouse rDNA. Primer A: intergenic spacer (IGS), primer B: promoter, primer C: 18S coding region, primer D: 28S coding region. Values of the average %IP (±standard deviation) for specific antibodies normalized to input DNA are shown on the bar graph. Positions of the upstream terminator T₀, rDNA promoter, pre-rRNA coding region and downstream terminators (T_1–10) are indicated in the scheme above. Error bars represent standard deviation of three independent experiments.