The Regulation of Intracellular Orthophosphate Concentration

Even though the intracellular concentration of orthophosphate (Pi) is an important influence on intracellular metabolism, its regulation is not well understood. In this paper a simple model is used to explain how cellular [Pi] is influenced by the transmembrane electrical potential and sodium distribution and by the kinetic properties of active and passive Pi transport, and how these factors affect the dependence of cellular [Pi] on extracellular [Pi] and its response to small displacements from equilibrium. Parts of the analysis are also applicable to other transported metabolites.