BAX

BAX (BCL-2-associated X protein) is a pore-forming protein whose oligomerization in the mitochondrial outer membrane commits a cell to apoptosis.

Function

BAX lives in the cytosol in an inactive, folded-shut state. Death signals activate BH3-only proteins, which expose BAX’s membrane-targeting helix; BAX moves to the mitochondrial outer membrane and, together with BAK, forms oligomeric pores. The outer membrane permeabilizes, cytochrome c and other intermembrane proteins escape, APAF1 assembles the apoptosome, and caspases execute the cell. Anti-apoptotic family members (BCL-2, BCL-xL, MCL-1) restrain BAX at each step, so whether BAX activates depends on the balance of opposing family members.

In cancer

BAX is a direct transcriptional target of p53, which places