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Development of an in vitro model system for studying the interaction of Equus caballus IgE with its high-affinity receptor FcεRI
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The structure of the IgE Cepsilon2 domain and its role in stabilizing the complex with its high-affinity receptor

J M McDonnell1, R Calvert, R L Beavil

  • 1The Rockefeller University, New York, New York 10021-6399, USA.

Nature Structural Biology
|April 27, 2001
PubMed

Insights

The Cepsilon2 domain of immunoglobulin E (IgE) significantly stabilizes its complex with the FcepsilonRI receptor on mast cells. This interaction explains the long-lasting sensitization crucial for allergic responses.

Area of Science:

  • Immunology
  • Structural Biology
  • Allergy Research

Background:

  • The stability of the IgE-FcepsilonRI complex on mast cells is key to allergic reactions.
  • IgE-FcepsilonRI complex has a long half-life, leading to mast cell sensitization and immediate allergic responses.

Purpose of the Study:

  • To investigate the role of the Cepsilon2 domain of IgE in the stability of the IgE-FcepsilonRI complex.
  • To elucidate the structural basis for the prolonged interaction between IgE and FcepsilonRI.

Main Methods:

  • Heteronuclear NMR spectroscopy to determine the structure of the Cepsilon2 domain.
  • Chemical shift perturbation assays to identify interactions between Cepsilon2 and FcepsilonRIalpha.
  • Sedimentation equilibrium to analyze the binding of Cepsilon2 to the IgE Cepsilon3-4 fragment.

Main Results:

  • Deletion of the Cepsilon2 domain from IgE increased the dissociation rate from FcepsilonRI by over 10-fold.
  • The Cepsilon2 domain directly interacts with FcepsilonRIalpha.
  • Cepsilon2 also binds to the Cepsilon3-4 fragment of IgE.

Conclusions:

  • The Cepsilon2 domain is critical for the long half-life of the IgE-FcepsilonRI complex.
  • Interactions of Cepsilon2 with both FcepsilonRIalpha and the IgE Fc fragment provide a structural explanation for the complex's exceptional stability.

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