Figure 3.
Bcl-xL binds directly to cytochrome C in vivo. (A) U-937/Bcl-xL cells were treated with 20 Gy of IR and harvested at 6 h. Total cell lysates were subjected to immunoprecipitation with anti-cytochrome C, and the protein precipitates were analyzed by immunoblotting with anti-Bcl-x. As a control, cell lysate was directly analyzed by immunoblotting with anti-Bcl-x to identify the Bcl-xL and Bcl-xS forms. anti-cyto C, anti-cytochrome C. (B) U-937 cells were fixed in 8% paraformaldehyde and prepared for frozen thin-section immunocytochemistry. Sections were incubated with anti-Bcl-x antibodies followed by goat anti-rabbit IgG conjugated to 14 nm of gold particles.