A dynamical model of the distributed interaction of intracellular signals.

The behaviour of cells is coordinated by a large array of different types of intracellular protein kinases, protein phosphatases and second messenger molecules. Current experimental evidence suggests that these kinases, phosphatases and other messengers form a vast complicated interconnected signalling network inside the cell. A generic model of this signalling network is presented which is specifically designed to examine the global properties that can be expected from a model based on the available knowledge of these molecular interactions. Different protein types are represented as nodes in a network that interact via a connection matrix. During interactions, idealised kinases and phosphatases activate and deactivate other protein types by altering the level of phosphorylation of their regulatory sites. The occupancy of regulatory sites on protein kinases and phosphatases in turn determines their activity. Monte Carlo simulations are carried out on ensembles of networks. Steady states and periodic behaviour are observed in these networks. We discuss the potential of this type of model for understanding cell behaviour.