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Updated: Jun 25, 2026

Static Adhesion Assay for the Study of Integrin Activation in T Lymphocytes
Published on: June 13, 2014
Ligand and cation binding are dual functions of a discrete segment of the integrin beta 3 subunit: cation
S E D'Souza1, T A Haas, R S Piotrowicz
1Department of Molecular Cardiology, Cleveland Clinic Foundation, Ohio 44195.
Abstract:
The alpha IIb beta 3 integrin binds Arg-Gly-Asp-containing (RGD-containing) ligands in a cation-dependent interaction. A fourteen amino acid sequence, beta 3 (118-131), and an antibody to it, inhibited ligand binding functions of alpha IIb beta 3, and a 1:1 stoichiometric beta 3 (118-131)-RGD complex was detected by mass spectroscopy. Cation binding to beta 3 (118-131) was demonstrated by terbium luminescence and mass spectroscopy. Notably, ligand displaced cation from the beta 3(118-131) peptide and also from purified alpha IIb beta 3. Thus, beta 3 (118-131), a highly conserved region in integrin beta subunits, binds both ligand and cation. Formation of a ternary complex between cation, ligand, and receptor, with subsequent displacement of cation from beta 3 (118-131) and a second site within the receptor, may be central to the mechanism of ligand recognition by integrins.
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