FIG. 1.

Bax integration into the mitochondrial membranes during apoptosis and after Bid treatment. (A) Mitochondria from HeLa cells cultured in the absence or presence of 1 μM staurosporine for increasing times were isolated and treated with 0.1 M Na₂CO₃ to produce alkali-sensitive (Att [attached]) and -resistant (Ins [inserted]) fractions. Both fractions were analyzed by Western blotting for the presence of Bax. Cox II was used as a gel-loading control. (B) Mitochondria from HeLa cells were incubated with 100 nM recombinant wild-type Bid and two Bid mutants (BidmIII-1 and BidmIII-3) for 15 min at 30°C, recovered by centrifugation, and treated with 0.1 M Na₂CO₃ as above. Various proteins were analyzed by Western blotting in alkali-sensitive (Att.) and -resistant fractions (Ins.). (C) Cytochrome c was analyzed by Western blotting in the mitochondrial suspension following incubation with wild-type and mutant Bid.