B-cell lymphoma 2 family protein (BCL-2 family)

B-cell lymphoma 2 family proteins are a group of structurally related proteins that regulate the intrinsic mitochondrial pathway of apoptosis. These proteins are classified as either anti-apoptotic (e.g., BCL-2, BCL-X, MCL-1) or pro-apoptotic, further divided into multi-domain pore-formers (e.g., BAX, BAK) and BH3-only proteins (e.g., BAD, BIM, PUMA, NOXA). They function primarily at the mitochondrial outer membrane, controlling the release of apoptogenic factors such as cytochrome c, which triggers caspase activation and cell death. BCL-2 family modulation is a major therapeutic strategy in cancer, as their dysregulation is associated with tumor survival, chemoresistance, and evasion of cell death. Multiple small-molecule inhibitors have been developed to target BCL-2 family proteins, though clinical use is limited by resistance mechanisms and toxicity related to tissue-specific apoptotic regulation.

Other names

BCL-2 proteinsB-cell lymphoma 2 proteinsBCL-XBAXBAKMCL-1BH3-only proteins (e.g., BAD, BID, BIM, PUMA, NOXA)

Inhibition of anti-apoptotic BCL-2 proteins, leading to apoptosis induction Promotion of mitochondrial cytochrome c release Direct binding to hydrophobic BH3 domain-binding grooves Displacement of pro-apoptotic proteins causing membrane permeabilization Sensitization to cellular stress leading to cell death