Figure 1.

(a) The building blocks of the finite state linear model: binding sites are represented by triangles, control functions by boxes and substance generators by diamonds. Dotted lines represent cases where the discrete output of one element is the input for another element. (b, c) Switching behaviour of the binding sites. The curve (b) is typical for processes with hysteresis characteristics of a system that does not instantly follow the forces applied to it, but reacts slowly, or does not return completely to its original state: that is, systems whose states depend on their immediate history. The threshold for switching the states of the binding sites in FSLM is state-dependent and results in a similar curve (c). [c] concentration of substance binding to binding site j; asso_j, disso_j, association and dissociation constants for binding site j; u, binding site not occupied; o, binding site occupied.