Fig. 1.

CBP can be covalently modified by SUMO-1 in vitro and in vivo. (A) Western blot analysis of in vitro sumoylation of CBP proteins immunoprecipitated from COS-1 cells. (B and C) Western blot analyses of immunoprecipitated endogenous CBP from HeLa cells with or without 10 mM NEM (B) or with EGFP-SUMO-1 transfection (C). (D) Schematic presentation of different CBP fragments analyzed by in vivo sumoylation assays. COS-1 cells transfected with various Flag-tagged CBP fragments along with EGFP-SUMO-1 as indicated were precipitated and immunoblotted with anti-Flag antibody. The arrowhead and arrow indicate SUMO-1-modified CBP or CBP fragments and unmodified CBP or CBP fragments, respectively.