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Static Adhesion Assay for the Study of Integrin Activation in T Lymphocytes
09:14

Static Adhesion Assay for the Study of Integrin Activation in T Lymphocytes

Published on: June 13, 2014

Lymphocyte function-associated antigen-1 binding residues in intercellular adhesion molecule-2 (ICAM-2) and the

J M Casasnovas1, C Pieroni, T A Springer

  • 1The Center for Blood Research and Harvard Medical School, Department of Pathology, 200 Longwood Avenue, Boston, MA 02115, USA.

Proceedings of the National Academy of Sciences of the United States of America
|March 17, 1999
PubMed

Insights

Intercellular adhesion molecule-2 (ICAM-2) binding sites differ between integrin types. ICAM-2

Area of Science:

  • Structural biology
  • Immunology
  • Cell adhesion

Background:

  • Intercellular adhesion molecules (ICAMs) mediate cell-cell interactions crucial for immune responses.
  • Integrin binding to ICAMs is essential for lymphocyte trafficking and activation.
  • Differences in ICAM structure influence integrin binding specificity.

Purpose of the Study:

  • To determine the precise binding site of lymphocyte function-associated antigen-1 (LFA-1) on ICAM-2.
  • To compare LFA-1 binding sites on ICAM-2 with those on other ICAMs and VCAM-1.
  • To understand how structural variations dictate integrin-ligand specificity.

Main Methods:

  • X-ray crystallography of ICAM-2.
  • Site-directed mutagenesis of ICAM-2 based on structural data.
  • Analysis of ICAM-1 and ICAM-3 binding sites in light of new structures.

Main Results:

  • The LFA-1 binding site on ICAM-2 is located on the upper half of domain 1, spanning the GFC beta-sheet and CD edge.
  • A critical acidic residue (Glu-37) in ICAM-2 ligates Mg2+ within the LFA-1 I domain.
  • ICAM-1 and ICAM-3 share similar LFA-1 binding sites, while VCAM-1, lacking an I domain, binds differently across domains 1 and 2.

Conclusions:

  • The LFA-1 binding site on ICAM-2 is structurally distinct from VCAM-1 binding sites, reflecting differences in integrin I domains.
  • ICAM-2's binding site presentation is optimized for interaction with the LFA-1 I domain groove.
  • Understanding these structural differences aids in designing targeted therapies for inflammatory and immune diseases.

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