The three-dimensional model of the hIL-6/hIL-6R complex. (A) A ribbon representation of hIL-6 in grey bound to shIL-6R in yellow (side view). (B and C) Space-fill representations showing the complementary structural and functional epitopes for the binding of hIL-6 onto the predicted structure of hIL-6R (B) and for the binding of hIL-6R onto the predicted structure of hIL-6 (C). Side chains are colored according to their chemical properties: aromatic, red; hydrophobic, yellow; hydrophilic, blue; and polar-uncharged, grey. (D) A schematic illustration of the hydrophobic and hydrophilic interactions predicted in the hIL-6/hIL-6R binding interface. hIL-6R and hIL-6 are positioned as in (B) and (C), respectively.