Able to form cytoplasmic structures termed death effector filaments. Enhances APAF1 and cytochrome c-dependent activation of pro-caspase-9 and consecutive apoptosis. Stimulates apoptosis through activation of caspase-3. Involved in activation of caspase-1 and caspase-5 as part of the NALP1 inflammasome complex which leads to processing and release of IL1B and IL18. Binds ATP.