Fig. 7. Force-velocity curves for dynein with a dynamic catch-bond.

(a) The average velocity is shown as a function of a constant load force (x axis) on the motor for three different ATP concentrations, i.e. 0.5mM (circles), 1mM (diamonds), and 2mM (triangles). Dynamic catch-bonding behavior was observed at or above 1mM ATP. (b) Schematic of the force-velocity curve for 2mM ATP in (a) showing the velocity domain (see dashed lines), i.e. v_min < v_c < v_max, where three motor forces coexist for one velocity, i.e. F₁, F₂ and F₃. The grey band represents the force domain in which the motor is unstable. Points P and Q are referred to in the text. (c) The predicted dependence of the stall force on the ATP concentration in the presence (upper curve) and absence (lower curve) of dynamic catch-bonding.