Fig. 1.

Liaisons in the Bcl2 family. The Bcl2 family can be categorized into three classes of proteins that control mitochondrial cell death by complex protein–protein interactions, indicated here. These interactions are based on different affinities between individual family members and are influenced by various post-translational protein modifications. Anti-apoptotic Bcl2, BclX, Bclw, Mcl1 and A1/Bfl1 show only partially overlapping binding preference for pro-apoptotic Bax and Bak. Selective binding is also intricate to individual BH3-only proteins that act as sensors of cell stress and bind selectively to one or more anti-apoptotic Bcl2 proteins while some can also interact directly with Bax or Bak to promote mitochondrial outer membrane permeabilization. For detailed information on the molecular mode of action, see [1,2].