Review Article

The Role of BCL2 Family of Apoptosis Regulator Proteins in Acute and Chronic Leukemias

Table 2

This table summarizes the properties of the most well-studied members of BCL2 family.

ActionMechanism of actionSubcellular localization

BCL2AntiapoptoticInhibits apoptosis by preservation of mitochondrial membrane integrity(i) Outer mitochondrial membrane
(ii) Nuclear envelope
(iii) Membrane of the endoplastic reticulum (ER)

BCL-XLAntiapoptoticInhibits cytochrome c release through the mitochondrial pore that inhibits activation of the cytoplasmic caspase cascade by cytochrome cTransmembrane molecule in the mitochondria

BCL-WAntiapoptoticReduced cell apoptosis under cytotoxic conditionsExclusively on the mitochondrion

MCL-1AntiapoptoticShort half-life, interaction with BAK1, Noxa, BCL2L11, Bcl-2-associated death promoter, PCNAMitochondria, nucleus

BAXProapoptotic Release of apoptogenic factors like cytochrome c, activation of caspase cascadeCytosol

BAKProapoptoticUndergoes conformational changes to form larger aggregates during apoptosisIntegral mitochondrial membrane protein

BIDProapoptoticDirect activator of BaxCytosol and membrane

BIMProapoptoticFree Bim binds to Bcl-2 or Bcl-XL and inactivates their antiapoptotic functionsFree BIM in mitochondria

BADProapoptoticDephosphorylated BAD forms a heterodimer with Bcl-2 and Bcl-xL, inactivating them and thus allowing Bax/Bak-triggered apoptosisFree BAD in mitochondria