Fig. 2.

The BH3-only protein tBID triggers FL-BAK–dependent mitochondrial and liposomal release. (A and B) tBID dose-responsively triggered FL-BAK–mediated cytochrome c release from isolated Bak^−/− mitochondria, as measured by cytochrome c ELISA. Likewise, FL-BAK dose-responsively induced cytochrome c release upon exposure to fixed-dose tBID. No release was observed upon exposure of the mitochondria to tBID or FL-BAK alone. Experiments were performed in duplicate and were repeated at least three times using independent FL-BAK preparations with similar results. Data are mean ± SD. (C) tBID dose-responsively induced FL-BAK–mediated liposomal release of entrapped fluorophore, whereas tBID or FL-BAK alone had little to no effect. Data are representative of at least three independent experiments with similar results.