FIGURE 1.

Measurement scheme. Two nanofabricated lever sets were employed, each held by a micromanipulator (Model Ts-5000-150, Burleigh, New York). A stationary lever of one set was used to hold the thick filament, whereas a deflectable lever of the other set was used to catch a single actin filament. Its deflection is a direct measure of F-actin translation along thick filament. Levers were precoated with nitrocellulose. Flexible levers have a stiffness of 0.18 pN/nm. A linear photodiode array was used to detect the positions of the three levers. The three peaks shown are taken from the respective images of the levers projected onto the linear photodiode array.