A shaker-like K+ channel with weak rectification is expressed in both source and sink phloem tissues of Arabidopsis
A shaker-like K+ channel with weak rectification is expressed in both source and sink phloem tissues of Arabidopsis
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DOI：
10.1105/tpc.12.6.837
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发表时间：
2000-06-01
期刊：
影响因子：
11.6
通讯作者：
Thibaud, JB
中科院分区：
文献类型：
--
作者：
Lacombe, B;Pilot, G;Thibaud, JB
RNA凝胶印迹和逆转录-聚合酶链反应实验被用来确定一个单一的K+通道基因在整个植物中表达的拟南芥。β-葡萄糖醛酸酶报告基因的使用揭示了该基因AKT 2/AKT 3在源和库韧皮部组织中的表达。AKT 2/AKT 3基因对应于两个先前鉴定的cDNA，AKT 2（在其5'端重建）和AKT 3，后者的开放阅读框在其5'端比前者短。用聚合酶链反应和定点突变快速扩增cDNA末端，以鉴定AKT 2翻译的起始密码子。所有数据都与编码的多肽对应于先前鉴定的最长开放阅读框（AKT 2）的假设一致。电生理特性（宏观和单通道电流）的AKT 2在非洲爪蟾卵母细胞和COS细胞揭示了一个独特的门控模式和敏感性pH值（弱内向整流，抑制，并增加内部或外部酸化整流），这表明AKT 2有足够的功能可塑性，执行不同的功能，在韧皮部组织的源和汇器官。植物胁迫激素脱落酸显示增加AKT 2转录物的量，表明AKT 2在植物对干旱的响应中的作用。
RNA gel blot and reverse transcription-polymerase chain reaction experiments were used to identify a single K+ channel gene in Arabidopsis as expressed throughout the plant. Use of the beta-glucuronidase reporter gene revealed expression of this gene, AKT2/AKT3, in both source and sink phloem tissues. The AKT2/AKT3 gene corresponds to two previously identified cDNAs, AKT2 (reconstructed at its 5' end) and AKT3, the open reading frame of the latter being shorter at its 5' end than that of the former. Rapid amplification of cDNA ends with polymerase chain reaction and site-directed mutagenesis was performed to identify the initiation codon for AKT2 translation. All of the data are consistent with the hypothesis that the encoded polypeptide corresponds to the longest open reading frame previously identified (AKT2). Electrophysiological characterization (macroscopic and single-channel currents) of AKT2 in both Xenopus oocytes and COS cells revealed a unique gating mode and sensitivity to pH (weak inward rectification, inhibition, and increased rectification upon internal or external acidification), suggesting that AKT2 has enough functional plasticity to perform different functions in phloem tissue of source and sink organs. The plant stress hormone abscisic acid was shown to increase the amount of AKT2 transcript, suggesting a role for the AKT2 in the plant response to drought.