Promotes cell death. Successfully competes for the binding to Bcl-X(L), Bcl-2 and Bcl-W, thereby affecting the level of heterodimerization of these proteins with BAX. Can reverse the death repressor activity of Bcl-X(L), but not that of Bcl-2. Appears to act as a link between growth factor receptor signaling and the apoptotic pathways. Forms heterodimers with the anti-apoptotic proteins, Bcl-X(L), Bcl-2 and Bcl-W. Also binds protein S100A10 (By similarity). The Ser-112/Ser-136 phosphorylated form binds 14-3-3 proteins. Interacts with AKT1 and PIM3 (By similarity). Interacts (via BH3 domain) with NOL3 (via CARD domain); preventing the association of BAD with BCL2 (By similarity). Interacts with HIF3A isoform 2 (via C-terminus domain); the interaction reduces the binding between BAD and BAX (PubMed:21546903). Interacts with GIMAP3/IAN4 and GIMAP5/IAN5 (PubMed:16509771). Colocalizes with HIF3A isoform 2 in the cytoplasm (PubMed:21546903). Upon phosphorylation, locates to the cytoplasm. 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. Phosphorylated on one or more of Ser-112, Ser-136, Ser-155 and Ser-170 in response to survival stimuli, which blocks its pro-apoptotic activity. Phosphorylation on Ser-136 or Ser-112 promotes heterodimerization with 14-3-3 proteins. This interaction then facilitates the phosphorylation at Ser-155, a site within the BH3 motif, leading to the release of Bcl-X(L) and the promotion of cell survival. Ser-136 is the major site of AKT/PKB phosphorylation, Ser-155 the major site of protein kinase A (CAPK) phosphorylation. Methylation at Arg-131 and Arg-133 by PRMT1 inhibits Akt-mediated phosphorylation at Ser-136. Belongs to the Bcl-2 family. The protein name 'Bcl2 antagonist of cell death' may be misleading. The protein antagonises Bcl2-mediated repression of cell death, hence it promotes apoptosis.