Remodeling for demolition: changes in mitochondrial ultrastructure during apoptosis.

The release of Cytochrome c from mitochondria is a pivotal event in the apoptotic process, but the precise mechanisms remain controversial. A recent paper proposes that this involves two steps, one involving permeabilization of the mitochondrial outer membrane and a second in which the structural organization of the cristae changes to make Cytochrome c accessible for release. Both events are induced by proapoptotic members of the Bcl-2 family and appear to be separable.