Journal Article

Regulation of the H<sup>+</sup> Pump Activity in the Plasma Membrane of Internally Perfused <i>Chara corallina</i>

Izuo Tsutsui and Taka-aki Ohkawa

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 42, issue 5, pages 531-537
Published in print May 2001 | ISSN: 0032-0781
Published online May 2001 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pce068
Regulation of the H+ Pump Activity in the Plasma
Membrane of Internally Perfused Chara
corallina

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  • Biochemistry
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  • Plant Sciences and Forestry

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The role of cytoplasm for the maintenance of the H+ pump activity in Chara corallina internodal cells was examined by the intracellular perfusion technique. Cytoplasm-rich and -poor states were obtained by changing the perfusion time, short-term (less than 2 min) and long-term (more than 5 min), respectively. A large portion of cytoplasm was left by short-term perfusion but most of the cytoplasm was removed by long-term perfusion. The activities of the H+ pump of these two different conditions were examined by measuring current-voltage relation (I-V curve) and conductance-voltage relation (G-V curve) under voltage clamp conditions. The H+ pump conductance decreased to 37%, 9% and zero by short-term, long-term and hexokinase perfusion, respectively, whereas the passive channel conductance decreased to 71%, 39% and 73% by short-term, long-term and hexokinase perfusion, respectively. On the other hand, the electromotive-force of the H+ pump (~ –260 mV) and the passive channel (~ –130 mV) were not affected by either short- or long-term perfusion. It is indicated that the cytoplasm plays an essential role to regulate the activity of both the H+ pump and the passive channel together with ATP.

Keywords: Key words: ATP — Chara — Cytoplasm — EMF — H+ pump — Intracellular perfusion.; Abbreviations: APW, artificial pond water; DCCD, dicyclo-hexylcarbo-diimide; EMF, electromotive-force; HK, hexokinase; IPM, internal perfusion medium.

Journal Article.  4685 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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