Figure 3.

Two-parameter bifurcation diagrams (k_1M versus Cdk) for the models in Figs. 1 and 2. (A) The model with singly phosphorylated substrates has a single domain of bistability. (B) The model with doubly phosphorylated substrates has two domains of bistability. Regions where the steady-state levels of phosphorylated substrates (S_P and M_P in A and S_PP and M_PP in B) are high or low are indicated. Other parameter values used in these calculations are given in Supplement 1 of the Supporting Material.