Fig. 2: The crystal structure of the FZD3 CRD in complex with Nb8 and Wnt surrogate luciferase assay.
From: Structural insights into Frizzled3 through nanobody modulators
a Cartoon representation of FZD3 CRD, coloured according to consurf alignment of the 10 human FZD CRD sequences. Nb8 coloured in blue (CDR1), green (CDR2) and red (CDR3). b FZD3 CRD superimposed with FZD8-Wnt3 complex (PDB 6AHY). Wnt3 is shown as teal tube and the lipid (palmitoleic acid, PAM) as magenta spheres. The aligned FZD8 CRD is hidden for clarity. c Close up view of FZD3 lipid binding groove compared to the groove of FZD8 bound to Wnt3. d FZD3 CRD superimposed with FZD8 dimer (as light grey and teal surface, PDB 6AHY). e A schematic representation of the Wnt surrogate encompassing comprising Nb8 (in wheat), which binds to FZD3 (black) linked (via a flexible linker in blue) to the C-terminal module of Dickkopf1 (DKK1C, magenta) which binds to the Wnt co-receptor LRP6/5 (grey). f Luciferase reporter-based Wnt signalling assays in FZD1–10-/- HEK293T cells and STF control. Normalized TOP-Flash luciferase activity was induced by the Wnt surrogate. Cells were transfected with either wild-type FZD3 or FZD3_Bril (denotes FZD3 with a Bril fusion in its ICL3 between TM-5 and TM-6). The STF cells were induced with L-cell Wnt-3a conditional media (bar with shading) as a positive control for comparison. Each dot indicates a sample value. (n = 9, three biological experiments with triplicates, the error bars are presented as mean values +/-SD).
