Figure 4.

Possible mechanisms for the negative stiffness and the linearization component. Using the bundle force versus displacement response with D = 5 μm²/s in Fig. 3A, force (top) and stiffness (bottom) responses are calculated by varying the rotational stiffness of the rootlet and the parameter r_b. (A) Generation of the negative bundle stiffness by decreasing the stiffness of the rootlet (with fixed r_b = 22 nm). (B) Linearized bundle force responses by increasing r_b (with fixed k_rootlet= 0.2 fN/rad). See Table 1 for the parameters used. See Fig. S10 for results obtained without considering the stiff protein region. To see this figure in color, go online.