Additional file 5: Figure S4. of Structural basis for potency differences between GDF8 and GDF11

Binding of GDF11 to the type I receptor ALK5. A, B, C Steady state analysis for SPR traces shown in Fig. 7b and calculated values. The maximum response at each concentration is plotted to a steady state binding equation using Biacore T200 Evaluation Software version 1.0 (Biacore). Sensorgrams were double referenced using an average of two 0 nM ligand injections. Ligand sources: GDF8 and GDF11, gift from Acceleron Pharma; Activin A, Activin B, and TGFβ3, produced and purified as described in “Methods.” D, E, F Ligand binding to Fc-ActRIIB-ECD (A), Fc-ALK5-ECD (B), and ALK5-ECD (C) amine coupled to a CM5 biosensor chip. Ligands were at 500 nM. TβRII, the type II receptor, was required for TGFβ3 binding to Fc-ALK5-ECD and ALK5-ECD. The receptor concentration was at 1 μM for this experiment. Experiments were performed using 40 μL/min flow rate at 37 °C. (TIF 1166 kb)