Anti-apoptotic protein known as inhibitor of apoptosis (IAP) which can regulate cell death by controlling caspases and by acting as an E3 ubiquitin-protein ligase (PubMed:14765125, PubMed:15200957, PubMed:18329369). Unlike most IAPs, does not contain a RING domain and it is not a RING-type E3 ligase (PubMed:15200957, PubMed:36758104, PubMed:36758105, PubMed:36758106). Instead acts as a dual E2/E3 enzyme that combines ubiquitin conjugating (E2) and ubiquitin ligase (E3) activities in a single polypeptide (PubMed:15200957, PubMed:36758104, PubMed:36758105, PubMed:36758106). Ubiquitination is mediated by a non- canonical E1 ubiquitin activating enzyme UBA6 (PubMed:36758104, PubMed:36758105, PubMed:36758106). Ubiquitinates CASP3, CASP7 and CASP9 and inhibits their caspase activity; also ubiquitinates their procaspases but to a weaker extent (PubMed:15200957, PubMed:36758104, PubMed:36758105, PubMed:36758106). Ubiquitinates pro-apoptotic factors DIABLO/SMAC and HTRA2 (PubMed:15200957, PubMed:36758104, PubMed:36758105, PubMed:36758106). DIABLO/SMAC antagonizes the caspase inhibition activity of BIRC6 by competing for the same binding sites as the caspases (PubMed:18329369, PubMed:36758106). Ubiquitinates the autophagy protein MAP1LC3B; this activity is also inhibited by DIABLO/SMAC (PubMed:36758105). Important regulator for the final stages of cytokinesis (PubMed:18329369). Crucial for normal vesicle targeting to the site of abscission, but also for the integrity of the midbody and the midbody ring, and its striking ubiquitin modification (PubMed:18329369). {ECO:0000269|PubMed:14765125, ECO:0000269|PubMed:15200957, ECO:0000269|PubMed:18329369, ECO:0000269|PubMed:36758104, ECO:0000269|PubMed:36758105, ECO:0000269|PubMed:36758106}. This is the function of Ensembl gene identifier ENSG00000115760 (BIRC6, baculoviral IAP repeat containing 6).