Fig. 7.

Proposed model of the M10HMM translocation along a single actin filament incorporating mechanical data from study. Initial binding of M10HMM to F-actin occurs via a leading head (A), is followed by an initial rapid phase of the power stroke giving 15 nm of movement (phase 1; B), and then a subsequent 2 nm (phase 2; C). Then, if the external load on the molecule is <1 pN, the trailing M10HMM head may swing forward and bind at the next available actin site (36 nm) in front and therefore becomes the new leading head (D), allowing processive stepping movement to proceed. However, if the load exceeds 1 pN, the leading head detaches before the trailing head has a chance to bind so that the M10HMM molecule then detaches from F-actin, which terminates the processive movement (E).