FIGURE 21-41 Structure of the nematode apoptosome and a model for the structure of the mammalian Apaf-1 apoptosome. (a) Domains of the CED-4 protein and the corresponding mammalian Apaf-1; CARD stands for N-terminal caspase recruitment domain. In the oligomeric apoptosome, these CARD domains bind to CARD domains in the caspases. (b) Diagram of the CED-4 apoptosome (left) and a model for the corresponding mammalian apoptosome (right). (c) Three-dimensional structure of the nematode octameric CED-4 apoptosome, showing the binding of two CED-3 procaspases. Interaction of the apoptosome with CED-3 stimulates CED-3 dimerization, which is necessary for its activation.

[Data from S. Qi et al., 2010, Cell 141:446, PDB ID 3lqr.]