BAK: Proteins and Enzymes

Bcl-2-antagonist/killer (BAK), also known as BAK1 and Bcl-2-like Protein 7, is a proaptoptotic member of the Bcl-2 protein family with a predicted molecular weight of approximately 23 kDa. It contains four Bcl-2 homology domains, BH1-BH4, and a C-terminal transmembrane domain. Human BAK shares 77% amino acid sequence identity with the mouse and rat orthologs. BAK primarily localizes to the outer mitochondrial membrane where it is redundantly required, along with Bax, for the release of Cytochrome c during apoptosis. Cytochrome c release may occur through pores formed by homo-oligomerization of BAK within the mitochondrial outer membrane. BAK can be directly activated by BID, BIM, and PUMA, which are also members of the Bcl-2 family. Additionally, p53 can directly activate BAK in response to cell stress. BAK may also be involved in crosstalk between the apoptosis and autophagy pathways.