Fig. 2.

Talin detects oscillatory signals among mechanical noise. (A) (Left) Dynamics of the talin R3 IVVI domain under mechanical white noise with an average of 9 pN and an SD of 2.8 pN. (Inset) Detail of the trajectory with the idealized trace (red). (Right) Comparison of the dwell-time histograms in the unfolded state perturbed by a constant force of 9 pN (black) and external mechanical noise (gray). Both distributions are comparable, as talin remains insensitive to randomly fluctuating forces and responds only to the average perturbation. Histograms are built from 1,063 (no noise) and 704 transitions (noise). (B) (Left) Dynamics of the talin R3 IVVI domain perturbed by a force signal oscillating at 0.7 Hz, with an amplitude of 1 pN, and submerged in mechanical white noise with an SD of 2.8 pN. (Inset, Upper) Detailed of the idealized trace (red. (Inset, Lower) Detail of the force perturbation (red). (Right) Dwell-time histogram measured under such signal. The folding transitions are synchronized with the oscillating force, while the mechanical noise is ignored. These dynamics shift the shape of the dwell-time distribution, which shows resonance peaks at odd multiples of half of the period of the signal. The remnant stochastic behavior is appreciated as an underlying exponential distribution (red dotted line). Histogram is built with 2,295 transitions. Traces are acquired at a frame rate of 1–1.5 kHz, and smoothed with a Savitzky–Golay fourth-order algorithm with a 101-points box size.