Figure 1.

Cytochrome c (red spheres) is present mostly in the mitochondrial inner membrane space of healthy cells, but translocates to the cytosol when intrinsic apoptotic stimuli are present. Transfer RNA (middle) may interact with cytochrome c and prevent association with Apaf-1, blocking formation of the apoptosome complex (upper right). When active, the apoptosome begins a proteolytic cascade that results in membrane blebbing, nuclear condensation and irreversible cell death.