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- Title
Picomolar concentration of tentoxin affect Mg<sup>2+</sup> - and Ca<sup>2+</sup> - ATPase activities of plasma membrane vesicles from roots of winter wheat seedlings.
- Authors
Klotz, Martin G.; Bérczi, Alajos; Erdei, László; Liebermann, Bernd
- Abstract
Purified plasmalemma vesicles were isolated in the presence of 250 mM sucrose from roots of 14-day-old seedlings of winter wheat (Triticum aestivum L. Martonvásári-8) by phase partitioning of salt-washed microsomal fractions in a Dextran-polyethylene glycol two-phase system. and both Mg2+ and Ca2+-ATPase activities were detected. Orthovanadate-sensitive Mg2+-ATPase activity associated with the inside of right side-out plasmalemma (PM) vesicles (latency 98%) was inhibited 76% by 0.3 mM Ca2+, Ca2+-dependent ATPase activity located partly on the inside and partly on the outside of plasmalemma vesicles (latency 47%) was not affected by Mg2+, Mg2+-ATPase activity was inhibited by 68% and inhibition of Mg2+ activation by 0.3 mM Ca2+ partly disappeared in the presence of 10 pM tentoxin, a fungal phytotoxin. Mg2+-ATPase activity remained inhibited up to 10 nM tentoxin while at 1 μM tentoxin Mg2+ activation was as high as without tentoxin. K+-stimulation and vanadate inhibition was increased and decreased, respectively, by 100 pM-10 nM tentoxin. Ca2+-dependent ATPase activity was continuously increased by 1 pM-10 nM tentoxin, but at 1 μM tentoxin the stimulation disappeared. The effects of pM tentoxin on plasmalemma Mg2+-ATPase are discussed in relation to its influence on K+ transport in wheat seedlings.
- Subjects
CELL membranes; WHEAT; DEXTRAN; ADENOSINE triphosphatase; TOXINS; PLANT physiology; TENTOXIN
- Publication
Physiologia Plantarum, 1989, Vol 75, Issue 3, p405
- ISSN
0031-9317
- Publication type
Article
- DOI
10.1111/j.1399-3054.1989.tb04646.x