Andrews, Allison-Lynn, Holloway, John W., Puddicombe, Sarah M., Holgate, Stephen T. and Davies, Donna E. (2002) Kinetic analysis of the interleukin-13 receptor complex. Journal of Biological Chemistry, 277, (48), 46073-46078. (doi:10.1074/jbc.M209560200)
http://eprints.soton.ac.uk/26907/

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Official URL: http://dx.doi.org/doi:10.1074/...M209560200

Abstract

Interleukin (IL)-13 is a key cytokine associated with the asthmatic phenotype. It signals via its cognate receptor, a complex of IL-13 receptor α1 chain (IL-13Rα1) with IL-4Rα; however, a second protein, IL-13Rα2, also binds IL-13. To determine the binding contributions of the individual components of the IL-13 receptor to IL-13, we have employed surface plasmon resonance and equilibrium binding assays to investigate the ligand binding characteristics of shIL-13Rα1, shIL-13Rα2, and IL-4Rα. shIL-13Rα1 bound IL-13 with moderate affinity (KD = 37.8 ± 1.8 nM, n = 10), whereas no binding was observed for hIL-4Rα. In contrast, shIL-13Rα2 produced a high affinity interaction with IL-13 (KD = 2.49 ± 0.94 nM n = 10). IL-13Rα2 exhibited the binding characteristics of a negative regulator with a fast association rate and an exceptional slow dissociation rate. Although IL-13 interacted weakly with IL-4Rα on its own (KD > 50 µM), the presence of hIL-4Rα significantly increased the affinity of shIL-13Rα1 for IL-13 but had no effect on the binding affinity of IL-13Rα2. Detailed kinetic analyses of the binding properties of the heteromeric complexes suggested a sequential mechanism for the binding of IL-13 to its signaling receptor, in which IL-13 first binds to IL-13Rα1 and this then recruits IL-4α to stabilize a high affinity interaction.

Abbreviations: IL, interleukin; shIL-13Rα1, soluble human IL-13 receptor α chain 1; shIL-13Rα2, soluble human IL-13 receptor α chain 2; sIL-4Rα, soluble human IL-4 receptor; SPR, surface plasmon resonance, RU resonance units; STAT, signal transducers and activators of transcription; SA chip, streptavidin-coated sensor chip.

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