Actin dynamics regulates voltage-dependent calcium-permeable channels of the Vicia faba guard cell plasma membrane.
Actin dynamics regulates voltage-dependent calcium-permeable channels of the Vicia faba guard cell plasma membrane.
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DOI：
10.1111/j.1744-7909.2009.00859.x
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发表时间：
2009-10
影响因子：
11.4
通讯作者：
Wei Zhang;L. Fan
中科院分区：
文献类型：
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作者：
Wei Zhang;L. Fan
胞质游离Ca（2+）（[Ca（2+）]（cyt））是植物细胞信号转导中普遍存在的第二信使，[Ca（2+）]（cyt）的升高与质膜和内膜中的Ca（2+）渗透通道有关，这些通道受多种刺激物的调节。然而，关于Ca（2+）通道及其调节的知识在植物中仍然有限。在蚕豆（Vicia faba L.）中发现了一种电压依赖性Ca（2+）通道。采用膜片钳技术观察保护细胞质膜。这些通道对Ba（2+）和Ca（2+）都是可透过的，它们的活性可被微摩尔Gd（3+）抑制。通道的单位电导和反转电位依赖于跨膜Ca（2+）或Ba（2+）梯度。内向全细胞Ca（2+）（Ba（2+））电流、单一Ca（2+）通道的单位电流幅度和NP（o）均沿着膜超极化增加。药理学实验表明，肌动蛋白动力学可能作为这种类型的保卫细胞质膜的钙通道的上游调节器。细胞松弛素D，一种肌动蛋白聚合阻断剂，在单通道水平激活这些通道的NPo，并在全细胞水平增加电流幅度。但这些通道激活和电流增量可以抑制预处理与F-肌动蛋白稳定剂，鬼笔环肽。这种调节机制的潜在生理意义进行了讨论。
Free cytosolic Ca(2+) ([Ca(2+)](cyt)) is an ubiquitous second messenger in plant cell signaling, and [Ca(2+)](cyt) elevation is associated with Ca(2+)-permeable channels in the plasma membrane and endomembranes regulated by a wide range of stimuli. However, knowledge regarding Ca(2+) channels and their regulation remains limited in planta. A type of voltage-dependent Ca(2+)-permeable channel was identified and characterized for the Vicia faba L. guard cell plasma membrane by using patch-clamp techniques. These channels are permeable to both Ba(2+) and Ca(2+), and their activities can be inhibited by micromolar Gd(3+). The unitary conductance and the reversal potential of the channels depend on the Ca(2+) or Ba(2+) gradients across the plasma membrane. The inward whole-cell Ca(2+) (Ba(2+)) current, as well as the unitary current amplitude and NP(o) of the single Ca(2+) channel, increase along with the membrane hyperpolarization. Pharmacological experiments suggest that actin dynamics may serve as an upstream regulator of this type of calcium channel of the guard cell plasma membrane. Cytochalasin D, an actin polymerization blocker, activated the NPo of these channels at the single channel level and increased the current amplitude at the whole-cell level. But these channel activations and current increments could be restrained by pretreatment with an F-actin stabilizer, phalloidin. The potential physiological significance of this regulatory mechanism is also discussed.