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. Author manuscript; available in PMC: 2008 Jul 25.
Published in final edited form as: Cell. 2008 Jan 25;132(2):259–272. doi: 10.1016/j.cell.2007.12.030

Figure 4. The interactions of IL-4Rα with IL-4 and IL-13.

Figure 4

For clarity the overall complexes are shown above blowups of the site I IL-4 (A) and IL-13 (B) interfaces, with color scheme retained from Figure 1. Zoomed up region of the site I interfaces focuses on the IL-4Rα EF loop interactions with cytokine A and C helices (labeled). Key interacting residues are shown in stick representation, and the “mimicked” Arg and Glu hotspot residues found in both IL-4 and IL-13 are thicker sticks and colored cyan, with polar contacts drawn as dashed green lines. (C) “Open book” view of binding epitopes presented by IL-4 and IL-13 to IL-4Rα. The resulting IL-4 and IL-13 cytokine (shown as cylinders) positions after their respective IL-4Rα were superimposed shows the relative structural overlap of the cytokine site I binding sites. (D) Structure-based sequence alignment between the interacting portions of helices A and C of IL-4 and IL-13 with IL-4Rα, where contact positions are in red boxes, common hydrophobic core residues are highlighted in gray and “hot spot” residues are highlighted in cyan to coincide with panels (A), (B) and (C).