We have studied some features of K+ accumulation by glycolysing Mycoplasma mycoides var. Capri cells. We report that when Na+ is absent from the external medium, K+ accumulates up to the level predicted by the amplitude of the transmembrane electrical potential, delta psi m, measured by Rb+ and methyltriphenylphosphonium cation (TPMP+) distribution. Therefore, under these experimental conditions, the coupling mechanism of K+ uptake consists of a delta psi m-driven uniport. More important, when Na+ is present in the external medium, the level of K+ accumulation by glycolysing Mycoplasma cells is far too steep to be equilibrium with delta psi m (-120 mV for delta muK+ compared with −90mV for delta muRb+ or delta muTPMP+). Our results clearly indicate the presence in Mycoplasma of an active K+-transport system specifically stimulated by Na+. Furthermore, by controlling the amplitude of the energy-dependent delta muH+, we obtain strong evidence that this specific Na+-stimulated K+ transport is modulated by the transmembrane electrical potential. Finally, we show that ATP is consumed when such a transport system is in activity.
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December 1982
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Research Article|
December 15 1982
Cation transport mechanisms in Mycoplasma mycoides var. Capri cells. Na+-dependent K+ accumulation
Publisher: Portland Press Ltd
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© 1982 London: The Biochemical Society
1982
Biochem J (1982) 208 (3): 529–538.
Citation
M Benyoucef, J L Rigaud, G Leblanc; Cation transport mechanisms in Mycoplasma mycoides var. Capri cells. Na+-dependent K+ accumulation. Biochem J 15 December 1982; 208 (3): 529–538. doi: https://doi.org/10.1042/bj2080529
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