The Arabidopsis cax1 mutant exhibits impaired ion homeostasis, development, and hormonal responses and reveals interplay among vacuolar transporters
The Arabidopsis cax1 mutant exhibits impaired ion homeostasis, development, and hormonal responses and reveals interplay among vacuolar transporters
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DOI：
10.1105/tpc.007385
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发表时间：
2003-02-01
期刊：
影响因子：
11.6
通讯作者：
Hirschi, KD
中科院分区：
文献类型：
--
作者：
Cheng, NH;Pittman, JK;Hirschi, KD
拟南芥Ca2+/H+转运体CAX1（阳离子交换器1）可能是细胞内Ca2+水平的重要调节因子。在这里，我们描述了CAX1在细胞质上的初步定位以及CAX1突变体的分子和生化特性。我们发现这些突变体表现出50%的张力质体Ca2+/H+反转运活性降低，40%的张力质体v型H+易位atp酶活性降低，36%的张力质体Ca2+- atp酶活性增加，并且增加了假设的液泡Ca2+/H+反转运蛋白CAX3和CAX4的表达。cax1系在Mn2+和Mg2+胁迫条件下均表现出生长增强的趋势。突变体表现出植物发育改变，激素敏感性紊乱，生长素调控的启动子报告基因融合表达改变。我们提出CAX(1)调节了无数的植物过程，并讨论了观察到的表型与其他转运蛋白的代偿性改变。
The Arabidopsis Ca2+/H+ transporter CAX1 (Cation Exchanger1) may be an important regulator of intracellular Ca2+ levels. Here, we describe the preliminary localization of CAX1 to the tonoplast and the molecular and biochemical characterization of cax1 mutants. We show that these mutants exhibit a 50% reduction in tonoplast Ca2+/H+ antiport activity, a 40% reduction in tonoplast V-type H+-translocating ATPase activity, a 36% increase in tonoplast Ca2+-ATPase activity, and increased expression of the putative vacuolar Ca2+/H+ antiporters CAX3 and CAX4. Enhanced growth was displayed by the cax1 lines under Mn2+ and Mg2+ stress conditions. The mutants exhibited altered plant development, perturbed hormone sensitivities, and altered expression of an auxin-regulated promoter-reporter gene fusion. We propose that CAX(1) regulates myriad plant processes and discuss the observed phenotypes with regard to the compensatory alterations in other transporters.