Active Calpain Promotes Fibrin Clot Contraction By Strengthening the Coupling of Fibrin-Bound αIIbβ3 to the Platelet Cytoskeleton

Platelet-driven blood clot contraction reduces and compacts clot volume, promoting hemostasis while restoring blood flow past otherwise obstructive thrombi. Clot contraction is driven by traction forces in the range of tens of pN per platelet that are generated by platelet non-muscle myosin IIa and actin on αIIbβ3 bound to extracellular fibrin fibers. In an analysis of the kinetics of thrombin-induced clot formation and contraction in...