Clustering of the K+ channel GORK of Arabidopsis parallels its gating by extracellular K+.
Clustering of the K+ channel GORK of Arabidopsis parallels its gating by extracellular K+.
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DOI：
10.1111/tpj.12471
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发表时间：
2014-04
期刊：
影响因子：
--
通讯作者：
Blatt MR
中科院分区：
文献类型：
--
作者：
Eisenach C;Papanatsiou M;Hillert EK;Blatt MR
Gork是保卫细胞中唯一表达的外向整流型Kv样钾离子通道。它的活性受到严格调控，以促进K+外流以促进气孔关闭，并在ABA中升高，同时抑制内向整流性K+通道KAT1的活性。虽然KAT1的种群受到进出质膜的调节交通的影响，但对Gork及其在体内的分布和交通一无所知。我们使用带有荧光标记的Gork的转化来探索其在烟草表皮和拟南芥保卫细胞中的特征。这些研究表明，作为外部K+浓度的函数，Gork以可逆地解离的点状聚集。Puncta解离与Gork的门控依赖性平行，其反应速度与通道门控对外部离子条件变化的反应速度一致。K+通道阻滞剂Ba2+也能抑制细胞的解离。相比之下，共聚焦和蛋白质生化分析未能发现该通道大量的胞外和内吞流量。通过外部K+将Gork的门控转移到更正的电压，这一特性确保了通道只促进K+外流，而不考虑外部阳离子浓度。高于1 mm的外部K+离子也会增强高尔克电导。我们认为，斑点蛋白中的Gork聚集性与其门控和电导有关，反映了相关的构象变化和通道蛋白的去稳定化，可能是响应外部K+反应的通道门控的传递和协调的平台。
GORK is the only outward-rectifying Kv-like K+ channel expressed in guard cells. Its activity is tightly regulated to facilitate K+ efflux for stomatal closure and is elevated in ABA in parallel with suppression of the activity of the inward-rectifying K+ channel KAT1. Whereas the population of KAT1 is subject to regulated traffic to and from the plasma membrane, nothing is known about GORK, its distribution and traffic in vivo. We have used transformations with fluorescently-tagged GORK to explore its characteristics in tobacco epidermis and Arabidopsis guard cells. These studies showed that GORK assembles in puncta that reversibly dissociated as a function of the external K+ concentration. Puncta dissociation parallelled the gating dependence of GORK, the speed of response consistent with the rapidity of channel gating response to changes in the external ionic conditions. Dissociation was also suppressed by the K+ channel blocker Ba2+. By contrast, confocal and protein biochemical analysis failed to uncover substantial exo- and endocytotic traffic of the channel. Gating of GORK is displaced to more positive voltages with external K+, a characteristic that ensures the channel facilitates only K+ efflux regardless of the external cation concentration. GORK conductance is also enhanced by external K+ above 1 mm. We suggest that GORK clustering in puncta is related to its gating and conductance, and reflects associated conformational changes and (de)stabilisation of the channel protein, possibly as a platform for transmission and coordination of channel gating in response to external K+.
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DOI：
10.1085/jgp.99.4.615
发表时间：
1992-04
期刊：
The Journal of general physiology
影响因子：
--
作者：
Blatt MR
通讯作者：
Blatt MR
影响因子：
3.3
作者：
Deutsch E;Weigel AV;Akin EJ;Fox P;Hansen G;Haberkorn CJ;Loftus R;Krapf D;Tamkun MM
通讯作者：
Tamkun MM
影响因子：
4.3
作者：
BLATT, MR
通讯作者：
BLATT, MR
影响因子：
56.9
作者：
Alonso, JM;Stepanova, AN;Ecker, JR
通讯作者：
Ecker, JR
影响因子：
64.8
作者：
BLATT, MR;THIEL, G;TRENTHAM, DR
通讯作者：
TRENTHAM, DR