NEUTRALIZING DEATH. “The death repressors (Bcl-2/Bcl-XL ¼ ) and their antagonists (Bax/Bak/Bid ¼ ) share the capacity to homodimerize and to neutralize each others through heterodimerization, and, for some of them, to insert through a carboxyterminal hydrophobic transmembrane domain into the outer membrane of intracellular organelles such as the nucleus, endoplasmic reticulum and mitochondria.”
http://www.nature.com/cdd/journal/v9/n4/full/4400950a.html