Apoptosis regulator BAX (BAX) (BAX)

Apoptosis regulator BAX, also known as BCL2-associated X protein, is a pro-apoptotic member of the BCL-2 family that serves as a critical executioner of the intrinsic cell death pathway (UniProt Q07812). BAX functions as a molecular switch that, upon activation by BH3-only proteins or cellular stress signals, translocates from the cytosol to the mitochondrial outer membrane where it undergoes a major conformational change (Nature, 2008, 455:1076–1081). This process leads to BAX oligomerization and the formation of pores, causing mitochondrial outer membrane permeabilization (MOMP) and the subsequent release of cytochrome c into the cytoplasm to activate caspases (PubMed: 21490342). In many malignancies, BAX is downregulated or inhibited by the overexpression of anti-apoptotic proteins like BCL-2, allowing cancer cells to evade apoptosis and resist chemotherapy (Cancer Cell, 2017, 32:230-244). Therapeutic development has focused on small molecule activators like BTSA1 and BAM7 that directly bind to the BAX trigger site to overcome apoptotic blocks in cancer (Nature Chemical Biology, 2012, 8:366–374). Conversely, inhibiting BAX is explored as a method to prevent pathological cell loss in neurodegenerative diseases and ischemic conditions like myocardial infarction (NIH, PMC: 4507024). While 'Bax mRNA expression' is a common experimental measurement or biomarker used to assess apoptotic potential, the functional therapeutic target is the BAX protein itself.

Other names

BCL2-associated X proteinBCL2L4Bcl-2-like protein 4BCL2-associated X protein transcript variant 1

Small molecule activators bind to the N-terminal trigger site or the BH3-binding groove of BAX, inducing a conformational change that promotes its translocation from the cytosol to the mitochondrial outer membrane, where it oligomerizes to form lethal pores. Inhibitors, such as BAX-inhibiting peptides, work by preventing this translocation or the subsequent oligomerization process to preserve cell viability in degenerative contexts.