Force spectroscopy of LFA-1 and its ligands, ICAM-1 and ICAM-2 |
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Authors: | Wojcikiewicz Ewa P Abdulreda Midhat H Zhang Xiaohui Moy Vincent T |
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Affiliation: | Department of Physiology and Biophysics, University of Miami Miller School of Medicine, Miami, Florida 33136, USA. ewojcikiewicz@med.miami.edu |
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Abstract: | Single-molecule measurements of the interaction of leukocyte function-associated antigen-1 (LFA-1), expressed on Jurkat T cells, with intercellular adhesion molecules-1 and -2 (ICAM-1 and ICAM-2) were conducted using atomic force microscopy (AFM). The force spectra (i.e., unbinding force versus loading rate) of both the LFA-1/ICAM-1 and LFA-1/ICAM-2 interactions were acquired at a loading rate range covering 3 orders of magnitude (50-60,000 pN/s) and revealed a fast loading regime and a slow loading regime. This indicates that the dissociation of both complexes involves overcoming a steep inner and a wide outer activation barrier. LFA-1 binding to ICAM-1 and ICAM-2 was strengthened in the slow loading regime by the addition of Mg(2+). Differences in the dynamic strength of the LFA-1/ICAM-1 and LFA-1/ICAM-2 interactions can be attributed to the presence of wider barriers in the ICAM-2 complex, making it more responsive to a pulling force than the ICAM-1 complex. |
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