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. 1997 Apr 29;94(9):4481–4486. doi: 10.1073/pnas.94.9.4481

Figure 4.

Figure 4

CBP is a component of PERE-associated complexes. (A) Effects of antibodies to CBP or p300 in EMSAs. HeLa cell nuclear extract (5 μg) was preincubated for 1 hr at 4°C with antibody (1 μg) to p300 (lanes 2 and 3) or CBP (lanes 4–7) before incubation with radiolabeled PERE probe for 15 min at 37°C. Antibodies were as follows: 1, anti-p300 (C-20; Santa Cruz Biotechnology); 2, anti-p300 (Upstate Biotechnology, Lake Placid, NY; catalog no. 05-222); 3, anti-CBP (A-22; Santa Cruz Biotechnology); 4, anti-CBP (C-20; Santa Cruz Biotechnology). For lanes 6 and 8, the antibody was first preincubated with its antigenic peptide (A-22 P or C-20 P; Santa Cruz Biotechnology) for 2 hr at 4°C before mixing with nuclear extract. No antibodies were added in lanes 1 and 8. Complexes P1–3 are noted, and the complex supershifted by anti-CBP antibody in lane 4 is marked by an open arrowhead. (B and C) CBP mediates transactivation by E1A 243R when bound to the PCNA promoter. Five micrograms of pGAL4-CBP or GAL4 DBD alone was cotransfected into HeLa cells with 5 μg of G5PCNA-CAT reporter and 0.5 μg of either pCMV12S.FS or pCMV12S where indicated. A representative experiment is shown in B, and an average of three independent experiments performed in duplicate is shown in C with SD indicated.