Binding strength and activation state of single fibrinogen-integrin pairs on living cells

摘要

Integrin activation states determine the ability of these receptors to mediate cell-matrix and cell-cell interactions. The prototypic example of this phenomenon is the platelet integrin, αIIbβ3. In unstimulated platelets, αIIbβ3 is inactive, whereas exposing plate- lets to an agonist such as ADP or thrombin enables αIIbβ3 to bind ligands such as fibrinogen and von Willebrand factor. To study the regulation of integrin activation states at the level of single molecules, we developed a model system based on laser tweezers, enabling us to determine the rupture forces required to separate single ligand-receptor pairs by using either purified proteins or intact living cells.