The two-pore channel TPK1 gene encodes the vacuolar K+ conductance and plays a role in K+ homeostasis

被引:195
作者
Gobert, Anthony
Isayenkov, Stanislav
Voelker, Camilla
Czempinski, Katrin
Maathuis, Frans J. M. [1 ]
机构
[1] Univ York, Dept Biol Area 9, York YO10 5DD, N Yorkshire, England
[2] Univ Potsdam, Inst Biochem & Biol, D-14476 Golm, Germany
关键词
D O I
10.1073/pnas.0702595104
中图分类号
O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];
学科分类号
07 ; 0710 ; 09 ;
摘要
The Arabidopsis thaliana genome contains five genes that encode two pore K+ (TPK) channels. The most abundantly expressed isoform of this family, TPK1, is expressed at the tonoplast where it mediates K+-selective currents between cytoplasmic and vacuolar compartments. TPK1 open probability depends on both cytoplasmic Ca2+ and cytoplasmic pH but not on the tonoplast membrane voltage. The channel shows intrinsic rectification and can be blocked by Ba2+, tetraethylammonium, and quinine. TPK1 current was found in all shoot cell types and shows all of the hallmarks of the previously described vacuolar K (VK) tonoplast channel characterized in guard cells. Characterization of TPK1 loss-of-function mutants and TPK1-overexpressing plants shows that TPK1 has a role in intracellular K+ homeostasis affecting seedling growth at high and low ambient K+ levels. In stomata, TPK1 function is consistent with vacuolar K+ release, and removal of this channel leads to slower stomatal closure kinetics. During germination, TPK1 contributes to the radicle development through vacuolar K+ deposition to provide expansion growth or in the redistribution of essential minerals.
引用
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页码:10726 / 10731
页数:6
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