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. 2020 Jan 12;10(1):128. doi: 10.3390/biom10010128

Figure 1.

Figure 1

Mechanisms of Bcl-2 regulated apoptosis. Simplified apoptosis schemes showing the role of Bcl-2 proteins in apoptosis initiation differ between mammals (a) and nematodes (b). The Bcl-2 family members are indicated for M. musculus. Nematodes have a simplified activation of apoptosis where the BH3-only protein EGL–1 binds the sole prosurvival protein in the C. elegans genome CED-9. This event releases the caspase activating protein CED–4 to initiate the caspase cascade. In mammalian apoptosis, the BH3-only group of proteins antagonize the prosurvival Bcl-2 proteins releasing Bax, Bak, or Bok to oligomerize and form pores in mitochondria causing mitochondrial outer membrane permeabilization (MOMP). Cytochrome c release from the mitochondrion triggers the mammalian equivalent of CED-4, APAF-1, to oligomerize and initiate the activation of downstream caspases.