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Demonstration of catch bonds between an integrin and its ligand

¹ Woodruff School of Mechanical Engineering and ² Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA 30332
³ Wellcome Trust Centre for Cell-Matrix Research, Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, England, UK

Correspondence to Cheng Zhu: cheng.zhu{at}bme.gatech.edu

Binding of integrins to ligands provides anchorage and signals for the cell, making them prime candidates for mechanosensing molecules. How force regulates integrin–ligand dissociation is unclear. We used atomic force microscopy to measure the force-dependent lifetimes of single bonds between a fibronectin fragment and an integrin ₅β₁-Fc fusion protein or membrane ₅β₁. Force prolonged bond lifetimes in the 10–30-pN range, a counterintuitive behavior called catch bonds. Changing cations from Ca²⁺/Mg²⁺ to Mg²⁺/EGTA and to Mn²⁺ caused longer lifetime in the same 10–30-pN catch bond region. A truncated ₅β₁ construct containing the headpiece but not the legs formed longer-lived catch bonds that were not affected by cation changes at forces <30 pN. Binding of monoclonal antibodies that induce the active conformation of the integrin headpiece shifted catch bonds to a lower force range. Thus, catch bond formation appears to involve force-assisted activation of the headpiece but not integrin extension.

Abbreviations used in this paper: AFM, atomic force microscopy; FN, fibronectin; GPIb, glycoprotein Ib; m₅β₁, membrane ₅β₁; PZT, piezoelectric translator; tr₅β₁, truncated ₅β₁; VWF, von Willebrand factor.

© 2009 Kong et al.
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• Roca-Cusachs, P., Gauthier, N. C., del Rio, A., Sheetz, M. P. (2009). Clustering of {alpha}5{beta}1 integrins determines adhesion strength whereas {alpha}v{beta}3 and talin enable mechanotransduction. Proc. Natl. Acad. Sci. USA 106: 16245-16250 [Abstract] [Full Text]  
• Short, B. (2009). Fibronectin is a good catch for integrin. JCB 185: 1130-1130 [Full Text]  

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