Figure 2.

Wiring diagrams for a three-module decomposition of the intrinsic apoptotic pathway. (A) Initiator module. (B) Amplifier module. (C) Executioner module. Ovals and rectangles represent proteins in different activity states. Solid and dashed lines represent chemical reactions and regulatory signals, respectively. An arrow with two tails and one head represents the association of two proteins to form a complex. Black balls on the tails indicate a reversible association and dissociation reaction. An arrow with one tail and two heads indicates a complex that splits into two parts, with a chemical transformation (like degradation or inactivation) of at least one component. Five small circles represent degradation products. In B, the four BAXm icons represent a tetrameric complex that opens channels in the mitochondrial outer membrane. See text for details.