Fig 2. The Apc binding domain is required for the rapid regulation of Axin in Wingless-responding cells, but dispensable for Axin ADP-ribosylation.

Use of the WWE pull-down assay to identify Axin domains that are important for ADP-ribosylation. Lysates from third instar larvae expressing indicated transgene with the C765-Gal4 driver were incubated with GST-WWE beads. Axin-V5 is pulled down (pd) by WWE (A), indicating that Axin-V5 is ADP-ribosylated. AxinΔTBD-V5 (A), AxinΔPP2-V5 and AxinΔDIX-V5 (D) are not pulled down by WWE, whereas AxinΔRGS-V5 (B) and AxinΔArm-V5 (C) are pulled down by WWE, indicating that the Tnks, PP2A and Dsh binding domains are required for Axin ADP-ribosylation, whereas the Apc and Armadillo binding domains are dispensable.