Before revision:  We investigate the stochastic reaction kinetics of covalent modification cycles (CMCs) by analytical modelling and numerically exact Monte-Carlo simulation of the temporaly fluctuating concentrationx(t). The statistical behaviour of this simple network module turns out to be so rich that CMCs can be viewed as versatile and tunable noise generators.
After revision:  We investigate the stochastic reaction kinetics of covalent modification cycles (CMCs) by analytical modelling and numerically exact Monte-Carlo simulation of the temporally fluctuating concentration.