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Updated: Jun 20, 2025
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A TIRF Microscopy Technique for Real-time, Simultaneous Imaging of the TCR and its Associated Signaling Proteins
Published on: March 22, 2012
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Dynamics and Activation of Membrane-Bound B Cell Receptor Assembly
Hung N Do1, Mingfei Zhao1, S Munir Alam2,3
1Theoretical Biology and Biophysics Group, Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
Biorxiv : the Preprint Server for Biology
|July 19, 2024
Summary
Antigen binding to B-cell receptor complexes (BCR) increases flexibility and alters transmembrane helix arrangements, revealing key dynamics in B-cell activation. This study sheds light on the elusive antigen-dependent signaling mechanism.
Area of Science:
- Immunology
- Structural Biology
- Computational Biology
Background:
- B-cell receptor complexes (BCR) are crucial for adaptive immunity, mediating antigen recognition.
- The precise mechanism of antigen-dependent B-cell activation remains incompletely understood despite decades of research.
- Recent cryo-EM structures revealed the asymmetric organization of human B-cell antigen receptors (IgM and IgG).
Purpose of the Study:
- To investigate conformational changes in BCR upon antigen binding using molecular dynamics simulations.
- To elucidate the influence of membrane lipids on BCR conformational dynamics and activation.
- To identify key dynamical events associated with antigen-dependent BCR activation.
Main Methods:
- Extensive molecular dynamics simulations were performed.
- Conformational dynamics upon antigen binding were probed.
- The impact of membrane lipid environment was analyzed.
Main Results:
- Antigen binding induced increased flexibility in BCR regions distant from the binding site.
- Antigen binding altered the rearrangement of IgM transmembrane helices and Igα/Igβ interactions.
- These transmembrane rearrangements influenced localized lipid composition.
Conclusions:
- Identified two critical dynamical events linked to antigen-dependent BCR activation.
- Antigen binding triggers conformational shifts affecting intracellular signaling pathways.
- Membrane lipid rearrangements play a role in modulating BCR signaling upon antigen engagement.
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