Upon its release from the mitochondrial intermembrane space, cytochrome c (CYSC) binds to and causes an ATP-mediated conformational change in the cytoplasmic adaptor protein apoptotic protease‑activating factor 1 (APAF1). This conformational change triggers the formation of procaspase-9-activating oligomeric protein complex named apoptosome. The active caspase‑9 holoenzyme activates downstream effector caspases‑3 and ‑7. The activated effector caspases then cleave various cellular proteins.
