Chemomechanical regulation of myosin Ic cross-bridges: Deducing the elastic properties of an ensemble from single-molecule mechanisms
Fig 8
Elastic properties of an ensemble of myosin Ic molecules.
(a) The extension x of an ensemble of N myosin molecules as a function of the applied force. The slope of this effective force-extension relation of an ensemble of myosin Ic molecules increases as the total number of molecules declines. We assume a spring constant for myosin Ic of κ = 500 μN/m. Because each head bound to the actin filament contributes to the stiffness, larger ensembles are stiffer. (b) The release Δx after reducing the binding probability by β-fold as a function of force for different numbers of myosin heads. For a constant force of 20 pN an ensemble of N = 10 heads relaxes about 20 nm after decreasing the binding probability by a 100-fold (red line). (c) The release Δx after reducing the binding probability by 100-fold and the elasticity of individual myosin molecules by 10-fold as a function of force. Increasing the total number N of myosin heads weakens the dependence on the force.