Figure 2.

The BCL-2 family proteins and the mitochondrial permeability transition pore (mPTP). (A) BCL-2 family proteins regulate mitochondrial outer membrane permeabilization to induce apoptotic cell death, which is positively and negatively regulated by intracellular signaling molecules. (B) mPTP is a large conductance channel that is activated by Ca²⁺ overloading and ROS, inducing the rupture of mitochondrial membranes and eventual cell death. Although the molecular constituents of the mPTP continue to be disputed, it has been shown that the opening of the mPTP is regulated by intracellular signaling molecules.