Anti-apoptotic Bcl-2 Family Proteins Disassemble

Early in mitochondria-mediated apoptosis, the mitochon-drial outer membrane becomes permeable to proteins that, when released into the cytosol, initiate the execution phase of apoptosis. Proteins in the Bcl-2 family regulate this permeabili-zation, but the molecular composition of the mitochondrial outer membrane pore is under debate. We reported previously that at physiologically relevant levels, ceramides form stable channels in mitochondrial outer membranes capable of passing the largest proteins known to exit mitochondria during apopto