title: Membrane potential and cation permeability. A study with a nystatin-resistant mutant of Rhodotorula gracilis (Rhodosporidium toruloides).
abstract: Cells of a nystatin-resistant mutant of the obligatory aerobic yeast Rhodotorula gracilis displayed an electrical potential difference, delta psi, across the plasma membrane which was, in contrast to the wild-strain cells, virtually independent of the pH of cell suspensions down to 4.5. In addition, the delta psi in mutant cells was insensitive to extracellular K+ concentrations. The mutant cells failed to cotransport measurable amounts of H+ by the onset of monosaccharide transport and to take up K+ in exchange for H+. Taking into account the lower passive permeability of the mutant plasma membrane for cations, it has been concluded that the pH dependency of delta psi in wild-strain cells is correlated with the electrogenic leak of H+ back into the cells in course of increasing delta pH across the plasma membrane.
mesh_terms: D002462:Cell Membrane / Q000502:physiology; D002463:Cell Membrane Permeability / Q000187:drug effects; D004351:Drug Resistance; D008564:Membrane Potentials / Q000187:drug effects; D003904:Mitosporic Fungi / Q000502:physiology*; D009154:Mutation; D009761:Nystatin / Q000633:toxicity*; D012248:Rhodotorula / Q000235:genetics / Q000502:physiology*
chemical_list: D009761:Nystatin