Figure 7. Structures of the C-terminal CLTD subdomains of the Intimin and Invasin passenger domains.

The cysteine residues are depicted by spheres with the C-terminal cysteines shown as yellow spheres and the penultimate cysteine as purple spheres. The positioning of the cysteines and the resulting disulphide bonds may stabilize the binding surfaces of both Intimins and Invasins, allowing accurate interactions with their ligands.