FIGURE 4.

The interval distribution p(τ) (dashed lines) and the time-dependent elongation rate C(t) (solid lines) for the single-step (a), the two-step (b), and the three-step model (c). The parameters for the three-step model are k_b = 1 s⁻¹, k_u = 1 s⁻¹, k_o = 0.2 s⁻¹, and k_e = 0.1 s⁻¹, which gives the average elongation rate Ω₀ = (1/k_b + 1/ + 1/k_e)⁻¹ = 1/21 s⁻¹ and the effective on-rate ≡ k_o/(1 + k_u/k_b) = 0.1 s⁻¹. The parameters for the two-step model are determined so that they behave similarly, i.e., the on-rate k_on = and the elongation rate in the on-state for the two-step model given by = (1/Ω₀ – 1/)⁻¹. The insets show the behaviors at t ≈ 0 with the asymptotic curves (dotted lines).