The two regimes in the linear pathway model based on the master equation.

<p>(A-B) fast (<i>k</i>₊<i>c</i>₀ = 20<i>s</i>⁻¹, <i>k</i>₋ = 100<i>s</i>⁻¹, <i>γ</i> = 0.1<i>s</i>⁻¹, <i>α</i> = 100<i>s</i>⁻¹, <i>ζ</i> = 1) and (C-D) slow (<i>k</i>₊<i>c</i>₀ = 0.01<i>s</i>⁻¹, <i>k</i>₋ = 0.05<i>s</i>⁻¹, <i>γ</i> = 1<i>s</i>⁻¹, <i>α</i> = 25<i>s</i>⁻¹, <i>ζ</i> = 500) switching. (A,C) Protein number as a function of time from Gillespie simulations for CM (blue lines) and BM (red lines). (B) The probability distribution for <i>n</i> target proteins is unimodal for both AM (blue) and FM (red). (D) The probability distribution is bimodal for AM (blue) and remains unimodal for BM (red) but with a long tail in the slow switching regime.