A Thermodynamic Model of Monovalent Cation Homeostasis in the Yeast Saccharomyces cerevisiae
Cationic and heavy metal toxicity is involved in a substantial number of diseases in mammals and crop plants. Therefore, the understanding of tightly regulated transporter activities, as well as conceiving the interplay of regulatory mechanisms, is of substantial interest. A generalized thermodynamic description is developed for the complex interplay of the plasma membrane ion transporters, membrane potential and the consumption of energy for maintaining and restoring specific intracellular cation concentrations. This concept is applied to the homeostasis of cation concentrations in the yeast cells of S. cerevisiae. The thermodynamic approach allows to model passive ion fluxes driven by the…
Calcium- and potassium-permeable plasma membrane transporters are activated by copper inArabidopsisroot tips: linking copper transport with cytosolic hydroxyl radical production
Transition metals such as copper can interact with ascorbate or hydrogen peroxide to form highly reactive hydroxyl radicals (OH . ), with numerous implications to membrane transport activity and cell metabolism. So far, such interaction was described for extracellular (apoplastic) space but not cytosol. Here, a range of advanced electrophysiological and imaging techniques were applied to Arabidopsis thaliana plants differing in their copper-transport activity: Col-0, high-affinity copper transporter COPT1-overexpressing (C1 OE ) seedlings, and T-DNA COPT1 insertion mutant ( copt1 ). Low Cu concentrations (10 μ m) stimulated a dose-dependent Gd 3+ and verapamil sensitive net Ca 2+ influx in …