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首页> 外文期刊>Biophysical Chemistry: An International Journal Devoted to the Physical Chemistry of Biological Phenomena >Modulation of calcium and potassium permeation in plant TPC channels
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Modulation of calcium and potassium permeation in plant TPC channels

机译：植物TPC通道中钙和钾渗透的调节

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摘要

Plant two-pore channels (TPCs) are non-selective cation channels permeable both to monovalent potassium and divalent calcium. We previously developed a technique that allowed the simultaneous determination of the fluxes of these two ions across the channel by a combined use of patch-clamp and fluorescence. In this paper we studied how potassium and calcium fluxes were influenced by modification of cytosolic concentrations of K+ and Ca2+. A decrease in cytosolic calcium from 2 to 0.5 mM led to a shift of the activation curve of about + 60 mV; although at positive potentials currents were very similar, calcium ion permeation was significantly reduced and the ratio between the total and calcium-mediated current increased about two-fold. Upon removal of cytosolic potassium, in the presence of 2 mM cytosolic calcium, the voltage-dependent activation curve was not modified but a dramatic reduction of the currents at positive voltages was apparent. However, calcium permeation did not change significantly in this condition. This work demonstrated that the electrophysiological measurements alone were not capable to predict the extent of the flow of different ions through cation channels. The parallel use of calcium detection by fluorescent dyes proved to be a valuable tool for the correct quantification of the permeation mechanisms in non-selective ion channels.
机译：植物两孔通道（TPC）是非选择性阳离子通道，可渗透到一价钾和二价钙。我们以前开发了一种技术，其通过组合使用膜片钳和荧光来同时确定在通道上的这两离子的助熔。在本文中，我们研究了钾和钙通量如何受K +和Ca2 +的细胞溶质浓度的改性的影响。将胞质钙从2至0.5mm的减少导致激活曲线的偏移约+ 60mV;尽管在正电势电流非常相似，但钙离子渗透显着降低，总和钙介导电流之间的比率增加约两倍。在去除细胞溶胶钾后，在2mM细胞溶质钙的存在下，不改变电压依赖性活化曲线，但正电压下电流的显着降低是显而易见的。然而，在这种情况下，钙渗透并没有显着变化。这项工作表明，单独的电生理学测量不能通过能够通过阳离子通道预测不同离子的流动程度。通过荧光染料的钙检测的平行使用被证明是用于正确定量非选择性离子通道中的渗透机制的有价值的工具。

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