Anti-apoptotic protein which can regulate cell death by controlling caspases and by acting as an E3 ubiquitin-protein ligase. Has an unusual ubiquitin conjugation system in that it could combine in a single polypeptide, ubiquitin conjugating (E2) with ubiquitin ligase (E3) activity, forming a chimeric E2/E3 ubiquitin ligase. Its tragets include CASP9 and DIABLO/SMAC. Acts as an inhibitor of CASP3, CASP7 and CASP9. Important regulator for the final stages of cytokinesis. 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. Homodimer. Binds the activated, processed forms of CASP3, CASP6, CASP7 and CASP9. Interacts with RNF41, DIABLO/SMAC, HTRA2, KIF23/MKLP1, USP8/UBPY, BIRC5/survivin, MAP2K1/MEK1, RAB8A/RAB8, RAB11A/RAB11, PLK1, EXOC3/SEC6 and EXOC4/SEC8. Expressed in brain cancer cells. Inhibited by DIABLO/SMAC, HTRA2, CASP3, CASP6, CASP7 and CASP9. Note: This description may include information from UniProtKB.