The coordinated control of ion transport across the two major membranes of differentiated plant cells, the plasma and the vacuolar membranes, is fundamental in cell physiology. The stomata responses to the fluctuating environmental conditions are an illustrative example. Indeed, they rely on the coordination of ion fluxes between the different cell compartments. The cytosolic environment, that is an interface between intracellular compartments, and the activity of the ion transporters localized in the different membranes influence one each other. Here we analyse the molecular mechanisms connecting and modulating the transport processes at both the plasma and the vacuolar membranes of guard cells.