Fig. 4.

Galectins bind the N-glycans of the D3 domain of FGFR1 and induce differential clustering of the receptor. BLI analyses of the interaction between the full length FGFR1-Fc or a truncated variant of the receptor lacking the D1 domain (FGFR1ΔD1-Fc) (A); or FGFR1ΔD1-Fc and receptor truncation lacking the D1 and D2 (FGFR1ΔD1-D2-Fc) (B) and selected galectins. Equimolar concentrations of the proteins tested were bound to Protein-A sensors, incubated with recombinant galectins and association and dissociation were recorded with BLI. Schematic structures of receptor variants are shown (left panel). Representative results from at least three independent experiments are shown. C BLI epitope binning experiments with FGFR1-Fc and galectins (experimental scheme shown in the left panel). FGFR1-Fc was immobilized on Protein A sensors and incubated with saturating concentrations of first galectin or buffer (control). The sensors were then moved to a solution containing the second galectin and BLI curves were compared between the test set-up and control. Representative results from at least three independent experiments are shown. D Galectins induce clustering of FGFR1. DLS signals of recombinant FGFR1-Fc (left panel), galectins (middle panels) and mixtures of these proteins (right panels) are shown. DLS-estimated MW of proteins are shown. High molecular weight complexes are seen upon incubation of FGFR1-Fc and galectins, which are not detected in single protein samples