Figure 6: High force displaces the bound V_D1 from the vinculin-binding site in αC_M.

(a) Extension change of WT αC_M during force jump between ~8 and ~40 pN in the presence of 100 nM V_D1. (b) Extension change of L344P αC_M during the same force jump procedure. (c) The histogram of lifetime of V_D1 bound to αC_M at different forces. Red curves are fittings with exponential decay function from which the dissociation rates were obtained. The number of events observed in each condition is denoted by ‘n’ in figure panel. The data were obtained from three individual tethers. (d) The logarithm of the dissociation rate is roughly linearly dependent on force. Red line denotes linear fitting of the log-scaled force-dependent off-rate. From the slope, the transition distance is estimated to be ~1 nm, and the dissociation rate at no force is estimated to be 9.3 × 10⁻⁶ s⁻¹ by extrapolation based on the Bell’s model⁶⁹. Y error bars denote 95% confidence interval of off-rate estimation, X error bars denote the ~5% relative error of our force calibration method.