Fig. 2.
CBP or p300 is required for acetylating H3K18. (A) Computational image analysis of immunofluorescent micrographs after IMR90 siRNA transfections against p300 and CBP (18) (fig. S7). The fraction T SD of nonstaining nuclei is plotted, n = 4. (Inset) Typical micrographs. (B) Nuclear extract from dl1500-infected HeLa cells 24 hours p.i. was subjected to three successive immunoprecipitations (IP1 to IP3) with equal amounts of monoclonal antibody (mAb) M73 against e1a. One-tenth of the total IP and supernatant (Sup1 to Sup3) after each IP were subjected to Western blotting. Differences in post-translational modifications caused e1a to appear as a doublet. (C) Twofold increasing amounts of p300/CBP IPed from mock- or dl1500-infected HeLa cells were incubated with glutathione S-transferase (GST)–H3 N terminus or hypoacetylated nucleosomes plus acetyl-coenzyme A (18), and products were assayed by Western blotting with anti-H3K18ac or anti-H3K14ac. (D) Histones from MEFs transformed with a retrovirus vector expressing SV40 large T antigen or the parental MEFs (top) and from IMR90 fibroblasts mock-infected or infected with an Ad expression vector for SV40 large T antigen 24 hours p.i. (bottom) were subjected to Western blotting.