Figure 6.

Myosin isoforms are predicted to display varying types of behavior on elastic substrates due to differences in t_attach and t_build. (A) For motor parameters that correspond to skeletal muscle myosin, the unloaded $\overline{\text{t}}$_attach (solid line) was comparable to or larger than ${\text{t}}_{\text{build}}^{\text{fit}}$ (diamonds), producing values of $\overline{\text{t}}$_attach on spring-loaded filaments (open squares) longer than the simulation time of 1000 s for all values of K. (B) For parameters representative of nonmuscle myosin IIA, $\overline{\text{t}}$_attach transitions from values much less than ${\text{t}}_{\text{build}}^{\text{fit}}$ to values much greater than ${\text{t}}_{\text{build}}^{\text{fit}}$ at a threshold value of K, leading to a sharp increase in effective force production. (C) For parameters representative of a nonmuscle myosin IIB type motor, both $\overline{\text{t}}$_attach and ${\text{t}}_{\text{build}}^{\text{fit}}$ are large for all values of K. For all panels, the default parameters in Table 1 and isoform-specific parameters from Table 2 were used. Values of N_heads: (A) 500, (B) 50, and (C) 50. Data points for $\overline{\text{t}}$_attach are average values over 15 simulations of 1000 s, and ${\text{t}}_{\text{build}}^{\text{fit}}$ was calculated using a fit to the scaling relationship in Fig. 4. To see this figure in color, go online.