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. 2014 Dec 15;5:5340. doi: 10.1038/ncomms6340

Figure 3. Structural comparison of the IL-1 family cytokine ternary complexes.

Figure 3

(a) Structural alignment of IL-18/IL-18Rα/IL-18Rβ (blue) and IL-1β/IL-1RI/IL-1RAcP (4DEP, red) using the binary complex region. The backbone Cα RMSD between IL-18/IL-18Rα and IL-1β/IL-1RI is 4.35–4.36 Å. (b) The orientation of D2 and D3 from IL-18Rβ and IL-1RAcP in the complexes. The dotted lines show the approximate orientation of the longitudinal D2 and D3 axes. A close-up of the binary complex interface, which recognizes the co-receptor protein D2 domains, is also shown. (c) A comparison of IL-18/IL-18Rα/IL-18Rβ (blue) and IL-1β/IL-1RII/IL-1RAcP (3O4O, green). The backbone Cα RMSD was 4.39 Å surrounding the binary complex portion. (d) A close-up of the β4-β5 loops of the ligands in IL-18/IL-18Rα/IL-18Rβ (left) and IL-1β/IL-1RII/IL-1RAcP (right). (e) Superimposition of IL-18Rβ and IL-1RAcP (from 3O4O). The IL-18Rβ-D1 orientation relative to D2 is the opposite of IL-1RAcP.