FIG. 3.

A 25-residue sequence of axin is sufficient for binding and inhibition of GSK-3β. (A) Schematic of Myc-tagged GID constructs. GID-1 (aa 277 to 545), GID-2 (aa 320 to 429), GID-3 (aa 320 to 375), GID-4 (aa 350 to 429), GID-5 (aa 380 to 429), and GID-6 (aa 380 to 404) were coexpressed in oocytes with GSK-3β. GSK-3β binding to axin-GID fragments was assessed by coimmunoprecipitation, and GSK-3β activity was measured by tau phosphorylation (as in Fig. 1). (B) GID-6 (Xenopus GID) corresponds to a highly conserved region of axin shared between Xenopus, chick (cAxin), mouse (mAxin), and human (hAxin) sequences.