Figure 10.

Structures of representative intracellularly active toxins from single-chain protein AB₅ and binary toxin families. The TcdB structure corresponds to the open conformation. The enzymatic component of Iota toxin contains two structurally related domains: an interactive domain with a binding component and an enzymatic domain that shares a similar structure with that of the C3 enzyme. C3 lacks a receptor binding structure and binding component. CPD, cysteine protease domain; CROPs, combined repetitive oligopeptides. Figures were produced with the program MacPyMOL.