FIGURE 5.

Cardiolipin promotes Bax insertion into bilayers. A, TIRF images of Cy3-labeled Bax on DPPC-only bilayers (left) or with 7% cardiolipin (right). The lipid bilayers were first incubated with 500 pm tBid and 2 nm Bax for 1 h and then washed with alkali buffer (200 mm Na₂CO₃, pH 11.5, 2% glycerol) for 30 min. The remaining spots were Bax inserted into bilayers. B, numbers of the fluorophore spots in the images of A. Error bars show the S.D. of five independent experiments. ***, p < 0.001 between the data in the different bilayers. C, distribution of photobleaching steps of the spots left on lipid bilayers (93% DPPC and 7% cardiolipin), fitted with binomial distribution (n = 4).