Promotes cell survival. Blocks dexamethasone-induced apoptosis. Mediates survival of postmitotic Sertoli cells by suppressing death-promoting activity of BAX. Interacts with HIF3A (via C-terminus domain). Interacts with BOP. Loosely associated with the mitochondrial membrane in healthy cells. During apoptosis, tightly bound to the membrane. Expressed (at protein level) in a wide range of tissues with highest levels in brain, spinal cord, testis, pancreas, heart, spleen and mammary glands. Moderate levels found in thymus, ovary and small intestine. Not detected in salivary gland, muscle or liver. Also expressed in cell lines of myeloid, fibroblast and epithelial origin. Not detected in most lymphoid cell lines. The BH4 motif seems to be involved in the anti-apoptotic function. The BH1 and BH2 motifs form a hydrophobic groove which acts as a docking site for the BH3 domain of some pro-apoptotic proteins. The C-terminal residues of BCL2L2 fold into the BH3-binding cleft and modulate pro-survival activity by regulating ligand access. When BH3 domain-containing proteins bind, they displace the C-terminus, allowing its insertion into the membrane and neutralizing the pro-survival activity of BCL2L2. Based on a readthrough transcript which may produce a BCL2L2-PABPN1 fusion protein. Belongs to the Bcl-2 family. Extended N-terminus.