FIG. 5.

CBP bromodomain is involved in physical and functional interaction with MyoD. (A) Nonmuscle cells (C3H 10T1/2) were transfected with expression vectors for MyoD and p300, either wild type (wt) or with the bromodomain deleted. Extracts were immunoprecipitated (ip) with an anti-p300 antibody and analyzed by Western blotting (wb) using an anti-MyoD antibody. (B) Expression of transfected proteins. Extracts of transfected cells were immunoprecipitated and analyzed by Western blotting using the indicated antibodies. (C) C3H 10T1/2 cells were microinjected with expression vectors for MyoD and for p300, either wt or with the bromodomain deleted, together with a rhodamine-coupled injection marker. After 40 h in differentiation medium, cells were fixed and immunostained with an antimyogenin antibody. Shown is the fraction of injected cells (rhodamine positive) which express myogenin; ▪, wt CBP; □, wt p300; ○, p300 delta Br.