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A conformation- and avidity-based proofreading mechanism for the TCR-CD3 complex
Wolfgang W A Schamel1, Ruth M Risueño, Susana Minguet
1Max Planck-Institut für Immunbiologie and University of Freiburg, Stübeweg 51, 79108 Freiburg, Germany.
Trends in Immunology
|March 11, 2006
Summary
T cells achieve high sensitivity and specificity through multivalent T-cell receptor (TCR-CD3) interactions with peptide-MHC complexes. This multivalent nature explains specificity and establishes response thresholds, enhancing T-cell recognition.
Area of Science:
- Immunology
- Biophysics
- Computational Biology
Background:
- T cells exhibit remarkable sensitivity, specificity, and dynamic range in antigen recognition.
- This recognition relies on low-affinity interactions between the T-cell receptor (TCR-CD3) complex and peptide-MHC (pMHC) ligands.
- Recent findings suggest TCR-CD3 exists as multivalent complexes and undergoes conformational changes.
Purpose of the Study:
- To propose a thermodynamic model explaining TCR-CD3-pMHC interaction specificity.
- To elucidate how receptor conformational changes establish response thresholds and kinetic properties.
- To suggest mechanisms for signal amplification in T-cell activation.
Main Methods:
- Development of a thermodynamic model for TCR-CD3-pMHC interactions.
- Analysis of receptor multivalent binding and conformational dynamics.
- Theoretical investigation of signal transduction and amplification pathways.
Main Results:
- Multivalency of the TCR-CD3 complex is proposed as the basis for specific pMHC recognition.
- Free energy barriers associated with conformational changes dictate response thresholds and recognition kinetics.
- Cooperative interactions within multivalent TCR-CD3 complexes enable signal amplification.
Conclusions:
- The multivalent nature of TCR-CD3 complexes is key to T-cell sensitivity and specificity.
- Thermodynamic principles govern T-cell receptor activation thresholds and recognition kinetics.
- Signal spreading across multivalent TCR-CD3 complexes amplifies the T-cell response.