title: Interaction of cations with phosphate uptake by Saccharomyces cerevisiae. Effects of surface potential.
abstract: The effect of bivalent cations on phosphate uptake by Saccharomyces cerevisiae was investigated. Phosphate uptake via the Na+-dependent transport system at pH 7.2 is stimulated by bivalent cations. The apparent affinity of phosphate for the transport mechanism is increased, but the apparent affinity for Na+ is decreased. Uptake of phosphate via the Na+-independent transport system is accompanied by a net proton influx of 2H+ and an efflux of 1 K+ for each phosphate ion taken up. At pH 4.5 phosphate uptake via the Na+-independent system is stimulated by bivalent cations, whereas at pH 7.2 uptake is inhibited. The effect of bivalent cations on phosphate uptake can be ascribed to a decrease in the surface potential.
mesh_terms: D001665:Binding Sites; D001692:Biological Transport / Q000187:drug effects; D002118:Calcium / Q000494:pharmacology*; D004594:Electrophysiology; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology*; D008956:Models, Chemical; D010710:Phosphates / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D012964:Sodium / Q000378:metabolism
chemical_list: D010710:Phosphates; D012964:Sodium; D008274:Magnesium; D002118:Calcium