Figure 5. Structural details of binding sites in the Norrin–Fz4CRD–SOS complex.
(A) Side-view of complex. Fz4CRD loops involved in Norrin binding are coloured blue (loop I), green (loop II), and yellow (loop III). (B–E) Views detailing the interfaces. Selected residues involved in binding are shown as sticks and coloured magenta (Norrin), blue (loop I), green (loop II), yellow (loop III), and cyan (Phe96 of Fz4CRD) and those associated with disease mutations are highlighted in boxes. Dotted lines denote hydrogen bonds. (B) Interactions between Fz4CRD loop I and Norrin. (C) Hydrophobic interactions of Norrin with Fz4CRD loop II and part of loop III. (D) Interactions of Fz4CRD loop III with Norrin. (E) SOS binding to Norrin and Fz4CRD loop III.