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Updated: Aug 15, 2026

Adhesion Frequency Assay for In Situ Kinetics Analysis of Cross-Junctional Molecular Interactions at the Cell-Cell Interface
13:22

Adhesion Frequency Assay for In Situ Kinetics Analysis of Cross-Junctional Molecular Interactions at the Cell-Cell Interface

Published on: November 2, 2011

Two-dimensional kinetics regulation of alphaLbeta2-ICAM-1 interaction by conformational changes of the

Fang Zhang1, Warren D Marcus, Nimita H Goyal

  • 1Coulter Department of Biomedical Engineering and Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA.

The Journal of Biological Chemistry
|October 20, 2005
PubMed

Insights

Leukocyte integrin alphaLbeta2

Area of Science:

  • Immunology
  • Cell Biology
  • Biophysics

Background:

  • Leukocyte integrin alphaLbeta2 is crucial for cell adhesion and migration in immune responses.
  • Conformational changes in the alphaLbeta2 integrin's I domain regulate ligand binding.

Purpose of the Study:

  • To investigate the conformational regulation of alphaLbeta2 binding affinity and kinetics.
  • To understand how I domain conformation affects ligand interactions and cation regulation.

Main Methods:

  • Micropipette aspiration technique used to measure 2D binding affinity and kinetics.
  • K562 cells expressing alphaLbeta2 or isolated I domain were utilized.
  • Disulfide bonds were employed to lock the I domain into specific conformations.

Main Results:

  • Locking the I domain into open/intermediate states increased affinity 8000-fold/30-fold compared to the closed state.
  • Affinity increases were primarily driven by enhanced on-rates, with modest decreases in off-rates.
  • Divalent cations (Mn2+, Mg2+) regulated wild-type alphaLbeta2 but not isolated I domain; this regulation was abolished when the I domain was locked.

Conclusions:

  • Downward displacement of the I domain C-terminal helix, driven by allosteric changes in other alphaLbeta2 domains, is essential for affinity and on-rate up-regulation.
  • Conformational flexibility of the I domain is critical for cation-mediated regulation of alphaLbeta2 function.

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