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. 1982 Dec 15;208(3):529–538. doi: 10.1042/bj2080529

Cation transport mechanisms in Mycoplasma mycoides var. Capri cells. Na+-dependent K+ accumulation.

M Benyoucef, J L Rigaud, G Leblanc
PMCID: PMC1154001  PMID: 6762210

Abstract

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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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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