FIGURE 9 

In all plots, p_TOT=100 and k_off=k_on=10, =0.01, k(t)=0.01(1+sin(t)), and =0.005. Phosphorylation and dephosphorylation rates are slower than the ones in Figure 8, that is, k₁=k₂=0.01, while the other parameters are left the same, that is, ₂=₂=10, ₁=₁=0.01, and Y_TOT=X_TOT=1500. (A) The signal X_p(t) without the downstream binding sites p is in green (solid line), while the same signal with the downstream binding sites p is in blue (dashed line). The effect of the retroactivity to the output s is dramatic. (B) The signal Z(t) without X in the system is in red (solid line), while the same signal Z(t) with X in the system is in black (dashed line). The device thus also displays a large retroactivity to the input r.