BIAcore analysis of interaction between IL4-Rα and the IL-13/IL13-Rα1 complex. BIAcore sensorgrams of the interaction between IL-4Rα and the binary complex of IL-13 and IL13-Rα1. IL-13 (1 μM) is perfused over a sensor chip with immobilized IL-13Rα1ECD to form a binary complex. After saturation of the immobilized IL13Rα1 chains with IL-13, IL4-RαECD (concentrations 1, 2.5, 5, 7.5, 10 μM) is perfused over the binary complex to measure the binding of the IL4-Rα chain to the complex of IL-13 and the IL13Rα1 chain. The apparent dissociation constant K
D of approx. 150 nM for the binding of the IL4Ra chain to the binary complex was calculated by evaluating dose dependency of equilibrium binding.