Induces caspases and apoptosis. Counters the protective effect of BCL2. Induces caspase activation and apoptosis (By similarity). Allows the release of cytochrome c (By similarity). Forms heterodimers either with the pro-apoptotic protein BAX or the anti-apoptotic protein BCL2. Interacts with PLEKHN1. Interacts with ITCH (By similarity). Interacts with MTCH2 (By similarity). When uncleaved, it is predominantly cytoplasmic (By similarity). Translocates to mitochondria as an integral membrane protein. Associated with the mitochondrial membrane. Intact BH3 motif is required by BIK, BID, BAK, BAD and BAX for their pro-apoptotic activity and for their interaction with anti-apoptotic members of the Bcl-2 family. TNF-alpha induces caspase-mediated cleavage into a major p15 and minor p13 and p11 products (By similarity). Cleaved by CASP6 into a major p15 and minor p13 products, leading to release of cytochrome c and subsequent nonalcoholic steatohepatitis (By similarity). Ubiquitinated by ITCH; ubiquitination results in proteasome-dependent degradation.