E3 ubiquitin-protein ligase involved in the regulation of pathogen and abiotic stress responses by facilitating degradation of MYB108/BOI. Attenuates cell death by preventing caspase activation. Has no effect on the stability of the DELLA proteins. Not regulated by MYB108/BOI. S-ubiquitinyl-[E2 ubiquitin-conjugating enzyme]-L-cysteine + [acceptor protein]-L-lysine = [E2 ubiquitin-conjugating enzyme]-L-cysteine + N(6)-ubiquitinyl-[acceptor protein]-L-lysine. Protein degradation; proteasomal ubiquitin-dependent pathway. Interacts with MYB108/BOS1 and the DELLA proteins GAI, RGA, RGL1, RGL2 and RGL3. Expressed in leaves, siliques, roots, flowering tissues and stigma tips. Up-regulated by pathogen, methyl violagen, salicylic acid, 1-aminocyclopropane-1-carboxylic acid (ACC) and salt. Down-regulated by methyl jasmonate and gibberellic acid. The N-terminal domain (1-150) prevents cell death by suppressing caspase-like protease activation. The WRD domain (178-214) is necessary for interaction with MYB108/BOS1. The RING-type zinc finger domain mediates binding to an E2 ubiquitin-conjugating enzyme. It is required for the ubiquitination activity, but dispensable and not sufficient for interaction with MYB108/BOS1 (PubMed:20921156). No effect on germination. Boi, brg1, brg2 and brg3 quadruple mutant shows a higher GA signaling resulting in a higher seed germination in the presence of paclobutrazol, precocious juvenile-to-adult phase transition and early flowering. Shares anti-apoptotic activity with IAP family proteins. However, it lacks the baculovirus IAP repeat (BIR) domain, which was shown to be essential for anti-apoptotic activity in other IAP family members (PubMed:21926169).