Fig. 9. Requirement of Wg can be by-passed by fusing Wg to human FZ5 or LRP6 and mutating the palmitoylation site of Wg reduces the activity of both chimeric receptors. (A) Schematic representation of human FZ5, TrkN-LRP6C, Wg-HFz5, Wg-TrkN-LRP6C. Wg was fused to the N terminus of human FZ5 to form Wg-HFz5. Both human FZ5 and Wg-HFz5 were fused with GFP at their C termini. Wg was also fused to the N terminus of TrkN-LRP6C to form Wg-TrkN-LRP6C. (B) Hyperactivity of Wg-HFz5 requires both Arrow and Dsh. S2 cells were treated with control-, Arrow- or Dsh-dsRNA, and transfected with the indicated plasmids. Luciferase activities were measured 48 hours after transfection. (C) Mutating C93, the potential palmitoylation site of Wg, reduces the signaling activity of Wg-HFz5. The membrane expressions of human FZ5, Wg-HFz5 and WgC93S-HFz5 were determined by membrane biotinylation and immunoblotting with anti-GFP antibodies (insert). (D) Wg-TrkN-LRP6C is a Dsh-dependent hyperactive chimeric receptor and mutating the palmitoylation site of Wg reduces the activity of this chimera. The membrane expressions of TrkN-LRP6C, Wg-TrkN-LRP6C and WgC93S-TrkN-LRP6C were determined by membrane biotinylation and immunoblotting with anti-TrkC antibodies (insert).