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Functional epitope of common gamma chain for interleukin-4 binding
Jin-Li Zhang1, Manfred Buehner, Walter Sebald
1Theodor-Boveri-Institut für Biowissenschaften (Biozentrum), Physiologische Chemie II, Universität Würzburg, Germany.
European Journal of Biochemistry
|March 5, 2002
Summary
Researchers identified key binding sites on the common gamma chain (gamma(c)) and Interleukin 4 (IL-4) for their receptor complex. This reveals crucial details about molecular recognition in cytokine signaling.
Area of Science:
- Immunology
- Molecular Biology
- Structural Biology
Background:
- Interleukin 4 (IL-4) mediates cellular responses via a receptor complex.
- The common gamma chain (gamma(c)) is a crucial component of the IL-4 receptor.
- Previous studies identified an IL-4 binding epitope on gamma(c).
Purpose of the Study:
- To precisely define the gamma(c) residues involved in IL-4 binding.
- To elucidate the molecular interactions between IL-4 and its receptor components.
- To understand the structural basis of gamma(c)-dependent cytokine receptor function.
Main Methods:
- Alanine-scanning mutational analysis of gamma(c) residues.
- Identification of specific amino acid residues involved in binding.
- Double-mutant cycle analysis to assess interaction cooperativity.
Main Results:
- Identified gamma(c) residues I100, L102, Y103, and L208 as major binding determinants.
- These residues form hydrophobic interactions with IL-4 residues I11, N15, and Y124.
- Demonstrated co-operative interactions between IL-4 and gamma(c) side chains.
Conclusions:
- Detailed molecular map of the IL-4/gamma(c) binding interface.
- Provides insights into the functional significance of gamma(c) mutations in X-linked severe combined immunodeficiency.
- Establishes a model for molecular recognition in gamma(c)-dependent cytokine receptor systems.