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pubmed:abstractText |
Through direct interaction with the voltage-dependent anion channel (VDAC), proapoptotic Bcl-2 family members such as Bax and Bak induce apoptogenic mitochondrial cytochrome c release and membrane potential (Deltapsi) loss in isolated mitochondria. Using isolated mitochondria, we showed that Bid and Bik, BH3-only proteins from the Bcl-2 family, induced cytochrome c release but not Deltapsi loss. Unlike Bax/Bak, the cytochrome c release induced by Bid/Bik was Ca(2+)-independent, cyclosporin A-insensitive, and respiration-independent. Furthermore, in contrast to Bax/Bak, Bid/Bik neither interacted with VDAC nor directly affected the VDAC activity in liposomes. Consistently, Bid/Bik induced apoptosis without Deltapsi loss, whereas Bax induced apoptosis with Deltapsi loss. These findings indicated the involvement of a different mechanism in BH3-only, protein-induced apoptogenic cytochrome c release.
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