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Tonoplast inorganic pyrophosphatase in Vicia faba guard cells |
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| Authors: | Catherine P Darley Lorna A Skiera Frederick D Northrop Dale Sanders Julia M Davies |
| Institution: | (1) Plant Laboratory, Department of Biology, University of York, P.O. Box 373, York YO1 5YW, UK, GB;(2) Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK, GB |
| Abstract: | Lysed guard-cell protoplasts of Vicia faba L. exhibited hydrolytic activity characteristic of tonoplast inorganic pyrophosphatase (V-PPase; EC 3.6.1.1). Activity was inhibited by the specific V-PPase inhibitor aminomethylenediphosphonate, stimulated by K+ (K m = 51 mM) and inhibited by Ca2+ (80 nM free Ca2+ was required for 50% inhibition at 0.27 mM free Mg2+). Patch-clamp measurements of electrogenic activity confirmed enzyme localisation at the tonoplast. This is the first report of V-PPase activity in guard cells; its possible involvement in stomatal opening is discussed. Received: 12 February 1998 / Accepted: 24 April 1998 |
| Keywords: | : Guard cell Pyrophosphatase (V-PPase) Stoma Tonoplast Vacuole Vicia (guard cells) |
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