Structural model for mouse Wnt3a-Fz8 interaction. (A) Overview of the mouse Wnt3a-Fz8-CRD complex. Wnt3a is in grey, Fz8-CRD in blue. The binding sites (site 1, yellow; site 2, red; pseudo site 3, pink) are highlighted and the respective residues marked. Close-up views of binding sites 1 (B) and 2 (C), and pseudo site 3 (D). (E) Alignment of Xenopus Wnt8 and mouse Wnt3a sequences. Mutations introduced into site 1 (yellow), site 2 (red) and site 3 (pink) are indicated.