Fig. S2.

Saturation effects in the sensitivity function. (A) Activation curves for the MWC model in Eq. 1, across a full range of ligand concentration, c. The parameters used here are $K_A={10}^{-2},K_I={10}^2,N=4,\hspace{0.17em}\text{and}\hspace{0.17em}{\epsilon }_0\in \left[\mathrm{0,60}\right]$. (B) $S\left(c,{\epsilon }_0\right)$ as c nears lower saturation. The solid black curves are $S\left(c,{\epsilon }_0\right)$ for the same parameters as in A, the dashed blue line is $S_{lower}\left(c,{\epsilon }_0\right)$ from Eq. S15, and the dotted black line is the scaling function $\frac{N}{4}\frac{c/K_A}{1+c/K_A}$. (C) $S\left(c,{\epsilon }_0\right)$ as c nears upper saturation. The solid black curves are plots of $S\left(c,{\epsilon }_0\right)$ for the same parameters as in A, the dashed red line is from Eq. S16, and the dotted black line is the scaling function $\frac{N}{4}\frac{1}{1+c/K_I}$.