In vivo treatments that modulate PPi-dependent H+ transport activity of tonoplast-enriched membrane vesicles from barley roots

Minobu Kasai, Masao Sasaki, Yoko Yamamoto, Hideaki Matsumoto

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6 Citations (Scopus)


The PPi-dependent H+ transport activity of tonoplast-enriched membrane vesicles prepared from barley roots was greatly reduced when the plants were grown for 4 or 5 days with an additional 3 raM KC1 in growth medium that contained only 0.1 mM CaCl2 in water. To characterize the mechanism of this reduction in activity, we attempted to treat barley roots with K+ ions, Cl-ions (or acetate), and A23187 (with or without Ca2+ ions), which might be expected to cause alkalization, acidification and mobilization of Ca2+ ions in the cytoplasm, respectively. One-day treatment of barley roots with K+ ions significantly decreased PPi--dependent H+ transport activity of prepared tonoplast-enriched membrane vesicles, while treatment with Cl- ions or acetate significantly increased the activity. A similar increase in the activity also occurred by treatment with Ca2+ ions alone or in combination with A23187. Determination of the PPi-hydrolyzing activity of membrane vesicles showed that changes in this activity by the various treatments were similar to those in the PPi-dependent H+ transport activity. The changes in ATP-dependent H+ transport activity of membrane vesicles caused by these treatments were small. These results indicate that the in vivo treatments had significant effects on the H+ transport activity of H+-PPi-ase, one of the two active vacuolar H+-pumps (H+-PPiase and H+-ATPase). In addition, these results suggest the possibility that changes in levels of cytoplasmic H+ or Ca2+ ions may be involved in modulation of the H+ transport activity of the vacuolar H+-PPiase during plant growth.

Original languageEnglish
Pages (from-to)549-555
Number of pages7
JournalPlant and Cell Physiology
Issue number4
Publication statusPublished - Jun 1 1993


  • In vivo treatment
  • PPi-dependent H+ transport
  • Tonoplast

ASJC Scopus subject areas

  • Physiology
  • Plant Science
  • Cell Biology

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