Fig. 3. Axin–GSK3β interactions. (A) Axin residues Phe388, Leu392, Leu396 and Val399 form a hydrophobic helical ‘ridge’ that packs into a hydrophobic groove formed between helix 262–273 (green surface) and the extended loop from 285–299 (yellow surface) in GSK3β. (B) The axin(383–401) peptide (magenta and white) makes only a single side chain hydrogen bond to GSK3β (green-yellow), from Arg395 to Asp264.