Interaction of the K+-channel KAT1 with the coat protein complex II coat component Sec24 depends on a di-acidic endoplasmic reticulum export motif
Interaction of the K+-channel KAT1 with the coat protein complex II coat component Sec24 depends on a di-acidic endoplasmic reticulum export motif
复制标题
DOI：
10.1111/j.1365-313x.2008.03658.x
复制
发表时间：
2008-12-01
期刊：
影响因子：
7.2
通讯作者：
Homann, Ulrike
中科院分区：
文献类型：
--
作者：
Sieben, Christian;Mikosch, Melanie;Homann, Ulrike
离子通道的正确功能不仅取决于对它们活性的控制，而且还取决于对膜中通道数量的调节。例如，已经提出植物K+通道KAT 1的密度可以通过控制其从其合成位点内质网（ER）的输出来调节。通道的质膜的有效运输被发现依赖于在蛋白质的C-末端的二酸ER输出信号。在酵母和哺乳动物中的研究表明，二酸ER输出基序是必不可少的ER衍生的外壳蛋白复合物II（COPII）囊泡的蛋白质的富集，并承认Sec 24 COPII外壳的一个组成部分。为了研究植物中是否也存在类似的机制，我们在蚕豆保卫细胞中使用荧光共振能量转移（FRET）测量分析了KAT 1与Sec 24在体内的相互作用。这些测量揭示了分别与青色荧光蛋白和黄色荧光蛋白融合的KAT 1和Sec 24之间的FRET信号，表明KAT 1和Sec 24之间的相互作用。FRET信号仅发生在ER的核周区域，并且依赖于KAT 1的二酸ER输出基序。总之，结果指出了KAT 1的ER输出的高度保守机制，其中通道通过二酸基序与Sec 24的结合被募集到COPII囊泡中。
The correct functioning of ion channels depends not only on the control of their activity but also on the regulation of the number of channels in the membrane. For example, it has been proposed that the density of the plant K+-channel KAT1 may be adjusted by controlling its export from its site of synthesis, the endoplasmic reticulum (ER). Efficient transport of the channel to the plasma membrane was found to depend on a di-acidic ER export signal in the C-terminus of the protein. Studies in yeast and mammals indicate that di-acidic ER export motifs are essential for enrichment of proteins into ER-derived coat protein complex II (COPII) vesicles and are recognized by Sec24 a component of the COPII coat. To investigate whether similar mechanisms also exist in plants we have analysed the interaction of KAT1 with Sec24 in vivo using fluorescence resonance energy transfer (FRET) measurements in Vicia faba guard cells. These measurements revealed a FRET signal between KAT1 and Sec24 fused to the cyan fluorescent protein and the yellow fluorescent protein, respectively, indicating an interaction between KAT1 and Sec24. The FRET signal only occurred in the perinuclear region of the ER and was dependent on the di-acidic ER export motif of KAT1. Together, the results point to a highly conserved mechanism for ER export of KAT1 whereby the channel is recruited into COPII vesicles via binding of the di-acidic motif to Sec24.