PMID: 36912Jun 13, 1979

Active K+ transport in Mycoplasms mycoides var. Capri. Relationships between K+ distribution, electrical potential and ATPase activity

Biochimica Et Biophysica Acta
G Leblanc, C Le Grimellec


The addition of 5 . 10(-5) M or less of dicyclohexylcarbodiimide to Mycoplasma mycoides var. Capri preferentially influences K+ influx rather than efflux and reduces by 30--40% the activity of the membrane-bound Mg2+- ATPase. Adding valinomycin to metabolizing cells does not markedly affect K+ distribution but induces a rapid and complete loss of intracellular K+ in non-metabolizing cells. Uncoupling agents such as dinitrophenol, carbonylcyanide p-trifluoromethoxyphenylhydrazone, dissipate the K+ concentration gradient only when combined with valinomycin. Variations in the merocyanine fluorescence intensity indicate that a transmembrane electrical potential (delta psi) is generated on cell energization. This delta psi, not affected by valinomycin or uncouplers when used alone, is collapsed by a mixture of both. No change in fluorescence intensity can be detected when glucose is added to dicyclohexylcarbodiimide treated organisms. These experiments suggest that the membrane-bound Mg-ATPase activity control K+ distribution in these organisms through the generation of a transmembrane electrical potential difference.


Jun 1, 1976·Proceedings of the National Academy of Sciences of the United States of America·S RamosH R Kaback
May 1, 1975·Journal of Bioenergetics·H Rottenberg
Jun 30, 1976·The Journal of Membrane Biology·A Waggoner
Jun 1, 1973·Proceedings of the National Academy of Sciences of the United States of America·H HirataF M Harold


Jan 1, 1981·European Journal of Biochemistry·M BenyoucefG Leblanc
Jan 1, 1981·European Journal of Biochemistry·M BenyoucefG Leblanc

Related Concepts

DNA-dependent ATPase
Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone
Plasma Membrane
Hydrogen-Ion Concentration
Resting Potentials
Mycoplasma mycoides

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