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Proceedings of the National Academy of Sciences of the United States of America logoLink to Proceedings of the National Academy of Sciences of the United States of America
. 1992 Dec 15;89(24):11701–11705. doi: 10.1073/pnas.89.24.11701

Potassium transport into plant vacuoles energized directly by a proton-pumping inorganic pyrophosphatase.

J M Davies 1, R J Poole 1, P A Rea 1, D Sanders 1
PMCID: PMC50624  PMID: 1334545

Abstract

Potassium is accumulated in plant vacuoles against an inside-positive membrane potential. The mechanism facilitating energized K+ transport has remained obscure. However, electrogenic activity of the inorganic pyrophosphatase (H(+)-PPase) at the vacuolar membrane is dependent on cytoplasmic K+, raising the possibility that the enzyme translocates K+ into the vacuole. Membrane currents generated by the H(+)-PPase were measured (using a patch clamp technique) in intact vacuoles isolated from Beta vulgaris storage tissue. A significant orthophosphate-dependent outward current mediated by the enzyme in reverse mode is evoked only when potassium is present at the vacuolar face of the tonoplast, suggesting that potassium is a translocated ion. Furthermore, current-voltage analysis of the effects of extravacuolar potassium and pH on the reversal potential of the H(+)-PPase-generated current points to direct translocation of K+ and H+ by the enzyme. Thus the H(+)-PPase represents a distinct class of eukaryote translocase and could facilitate vacuolar K+ accumulation in vivo.

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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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