A rice high-affinity potassium transporter (HKT) conceals a calcium-permeable cation channel
A rice high-affinity potassium transporter (HKT) conceals a calcium-permeable cation channel
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水稻高亲和力钾转运蛋白（HKT）隐藏钙渗透性阳离子通道
DOI：
10.1073/pnas.1000698107
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发表时间：
2010-04-13
影响因子：
11.1
通讯作者：
Luan, Sheng
中科院分区：
文献类型：
--
作者：
Lan, Wen-Zhi;Wang, Wei;Luan, Sheng
植物高亲和力K+转运蛋白（HKT）因其与介导高亲和力K+吸收的细菌和真菌转运蛋白的关系而得名。HKT家族成员是钠选择性单向转运体或钠-钾协同转运体的观点被广泛接受。我们已经发现，水稻HKT蛋白质之一也作为Ca 2+渗透阳离子通道，传导由广泛的一价和二价阳离子携带的电流。水稻HKT基因被命名为OsHKT 2;4，在几种细胞类型中表达，包括根毛和维管薄壁细胞。蛋白质定位于质膜，从而提供阳离子摄取和挤出的机制。这一发现违背了HKT蛋白既可以作为离子载体又可以作为通道的根深蒂固的教条。这项研究进一步扩展了HKT蛋白质的功能，以Ca 2+连接的过程，并在这样做，定义了一个以前未描述的类型的Ca 2+渗透阳离子通道在植物中。这项工作还提出了关于这个蛋白质家族在单子叶植物和双子叶植物分化后的进化变化的问题。
Plant high-affinity K+ transport (HKT) proteins are so named because of their relation to bacterial and fungal transporters that mediate high-affinity K+ uptake. The view that HKT family members are sodium-selective uniporters or sodium-potassium symporters is widely held. We have found that one of the rice HKT proteins also functions as a Ca2+-permeable cation channel that conducts current carried by a wide range of monovalent and divalent cations. The HKT rice gene, named OsHKT2;4, is expressed in several cell types, including root hairs and vascular parenchyma cells. The protein is localized to the plasma membrane, thereby providing a mechanism for cation uptake and extrusion. This finding goes against firmly entrenched dogma in showing that HKT proteins can function as both ion carriers and channels. The study further extends the function of HKT proteins to Ca2+-linked processes and, in so doing, defines a previously undescribed type of Ca2+-permeable cation channels in plants. The work also raises questions about the evolutionary changes in this protein family following the divergence of monocots and dicots.