Figure 5: The key residues involved in forming the ternary signalling complex.
From: The structural basis for receptor recognition of human interleukin-18
(a) The interactions in the IL-18 receptor binding Site I. In addition to the area surrounding the stable α-helix I, Asp132IL-18 at the tip of the β10-β11 hairpin exhibits ionic interactions with the structure, which are formed by the two unique disulfide bonds in IL-18Rα. (b) Interactions surrounding the IL-18 Site II. The key residue of Lys53IL-18 is recognized by the IL-18Rα acidic surface through multiple hydrogen bonds. (c) The interface between Site III of IL-18 and IL-18Rβ. In addition to His109IL-18/Tyr212Rβ stacking, multiple hydrogen bonds were observed: the His109IL-18 Nε-H to the Val211Rβ backbone carbonyl oxygen as well as the Lys112IL-18 Nζ-H to the Glu210Rβ side chain and Tyr212Rβ Oη.
