Figure 3
From: Properties of cell signaling pathways and gene expression systems operating far from steady-state
Covalent modification (CM) cycles are shifters. (A) Top. Diagram of the enzymatic cycle. Bottom. Dynamics of Ea and Ed for exponential accumulation of Ea. (B–E) Time courses of y (=S*/ST) for different values of the input xmax (in a heatmap scale). (F–I) Input-output curves at different times (in a heatmap scale). (B–I) Correspond to 4 different examples, as indicated: Ka = Kd = 0.01 (zeroth order regime, B,C,F and G) and Ka = Kd = 100 (first order regime, D,E,H and I), each of them with τEan = 0.01 (fast rising input, B,D,F and H) or τEan = 100 (slow rising input, C,E,G and I). The complete list of parameters values for each example is included in the Supplementary Information. (J–M) EC50 (J,L) and nH (K,M) vs time for the four examples considered in (B–I). The inset in panel L shows how each curve approaches steady-state (N–Q) EC50 (N,P) and nH (O,Q) vs time for different parameter sets corresponding to the zero-order regime (N,O) or the first order regime (P,Q). For each scenario (K = 100 slow, K = 100 fast, K = 0.01 slow, K = 0.01 fast), 100 random parameter sets were scanned, see Supplementary Information for details of the parameter scanning.
