FIGURE 5.

Panel a illustrates a rate model to minimally describe T-gate's effect on dwell times (actually, the steady-state natural lifetime). Such a simple model would doubtfully predict detailed measurements, e.g., the randomness (49). The dashed region that contains abstract states s₁ and s₂ describes the overall ATP uptake mechanism, which includes T-gate within a Michaelis-Menten structure. The state s₃ represents the remainder of kinesin's chemical cycle. A particular form of the force-dependent rate, k(F) = 1/τ(F), is taken from Eq. 10. Panel b provides a plot of dwell times from the rate model in panel a with parameters deduced by fitting to the model of Nishiyama et al. (33), fitting with better than visual accuracy. That the agreement with Nishiyama et al. is excellent is likely a result of the choice in Eq. 10, but this is not to state that our rate model is identical with theirs (e.g., in the manner [ATP] dependence is included). Used in panel b: δ = 3.10 nm, R₀ = 193, , k₋ = 137 s⁻¹, k(0) = 857 s⁻¹, k₃ = 137 s⁻¹, and T = 300 K.