PMC

(A) The converter of the lead head rotates while staying in the PPS fold (blue to green) to promote strong attachment. The transition towards the rigor fold of the converter (red) cannot occur since it would generate too much torque. (B and C), various possible dockings of the lead head on an actin filament are indicated. (B left) The rear head (red) is indicated using the rigor state of myosin VI (2BKH). This corresponds to the state that the rear head adopts after recoupling of the lever arm (R-fold converter). Assuming a rigid lever arm for the rear head, possible steps correspond to distances between the end of the rigid lever arm of the rear head (ending at residue 912) and the end of the of the lead head lever arm (which incorporates both the IQ motif ending at residue 835 and ~12 nm from the unfolded three-helix bundle lever arm extension). Possible dockings for the PPS lead head are indicated with a MD^ins2-IQ construct (with converter in the P-fold) – the possible dockings are in blue and those that are too far are in black or grey. (Right) Same model in a different orientation to highlight the azimuthal components of the various dockings. (C) The rear head (green) is indicated using the rigor state of myosin VI (2BKH) in which the converter is modeled with a P-fold and the lever arm after the IQ motif is indicated assuming a rigid lever arm. This corresponds to the state the rear head likely adopts after the swing of its converter but prior to the recoupling of its lever arm. Possible dockings for the PPS lead head are indicated with a MD^ins2-IQ-PTD construct (with converter in the P-fold). Only the site at 5.5 nm would allow the converter rotation of the lead and a transition of both heads together toward the rigor state (red). The docking sites of the lead head in black or grey cannot lead to a productive step. (Right) Same model in a different orientation to highlight the azimuthal components of the various dockings. (D) Different phases for the step of a dimeric myosin VI molecule: (1) Docking of the lead head, (2) Swing with a PPS converter of the lead head maintains the orientation of its lever arm without significant strain, allowing strong binding to actin and phosphate and MgADP release (MgADP can rebind, but MgATP cannot bind), (3) Detachment of the rear head by MgATP binding allows the converter fold transition and recoupling of the lever arm in the lead head to bias rebinding of the former rear head towards the minus end.

Time curves for the vibration-induced displacements/swings of critical shearer components. (a) Vibration-induced swing for front drum (b) Vibration-induced swing for front ranging arm. (c) Vibration-induced displacement for (d) Vibration-induced displacement for front haulage unit front walking unit (e) Vibration-induced displacement for (f) Vibration-induced displacement for body front supporting unit (g) Vibration-induced displacement for (h) Vibration-induced displacement for rear haulage unit rear supporting unit (i) Vibration-induced displacement for (j) Vibration-induced swing for rear ranging arm rear walking unit (k) Vibration-induced swing for rear drum.

Bypass prostheses. (A) Rear view of the donned body-powered bypass prosthesis. (B) Front view of the donned DEKA arm prosthesis.

Model of the wheelchair-user system composed of four rigid bodies representing arms (red), forearms (green), rear wheels (blue) and the remaining body and wheelchair elements (gray/black). Coordinates are represented in figure (A), where α is the upper arm angle with respect to the direction of motion, β is the forearm angle with respect to the direction of motion, θ is the rear wheel angular displacement, x is the forward displacement of the shoulder/wheelchair and η is the ramp inclination angle. Lengths are represented in figure (B), where Y is the relative vertical and H is the relative horizontal distance between the center of the rear wheels and the shoulder, A is the upper arm length, B is the forearm length, R_p is the pushrim radius, and R_w is the rear wheel radius.