The phosphorylation state of two serine residues within the C‐terminal domain of AtPIP2;1 (S280, S283) regulates its plasma membrane localization in response to salt and osmotic stress. Here, we investigated whether the phosphorylation state of S280 and S283 also influence AtPIP2;1 facilitated water and cation transport. A series of single and double S280 and S283 phosphomimic and phosphonull AtPIP2;1 mutants were tested in heterologous systems. In Xenopus laevis oocytes, phosphomimic mutants AtPIP2;1 S280D, S283D, and S280D/S283D had significantly greater ion conductance for Na⁺ and K⁺, whereas the S280A single phosphonull mutant had greater water permeability. We observed a phosphorylation‐dependent inverse relationship between AtPIP2;1 water and ion transport with a 10‐fold change in both. The results revealed that phosphorylation of S280 and S283 influences the preferential facilitation of ion or water transport by AtPIP2;1. The results also hint that other regulatory sites play roles that are yet to be elucidated. Expression of the AtPIP2;1 phosphorylation mutants in Saccharomyces cerevisiae confirmed that phosphorylation influences plasma membrane localization, and revealed higher Na⁺ accumulation for S280A and S283D mutants. Collectively, the results show that phosphorylation in the C‐terminal domain of AtPIP2;1 influences its subcellular localization and cation transport capacity.

中文翻译：

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磷酸化影响AtPIP2; 1的水和离子通道功能。

AtPIP2; 1（S280，S283）C端结构域中两个丝氨酸残基的磷酸化状态调节其质膜定位，以响应盐和渗透胁迫。在这里，我们调查了S280和S283的磷酸化状态是否也影响AtPIP2; 1促进了水和阳离子的运输。在异源系统中测试了一系列的单和双S280和S283磷酸模拟和磷酸无效AtPIP2; 1突变体。在非洲爪蟾卵母细胞中，磷酸化突变体AtPIP2; 1 S280D，S283D和S280D / S283D对于Na ⁺和K ⁺具有明显更高的离子电导率。，而S280A单磷酸空突变体具有更高的水渗透性。我们观察到AtPIP2; 1的水与离子迁移之间的磷酸化依赖性反比关系，二者均发生10倍的变化。结果表明，S280和S283的磷酸化影响通过AtPIP2; 1优先促进离子或水的运输。该结果还暗示其他监管机构还扮演着尚待阐明的角色。酿酒酵母中AtPIP2; 1磷酸化突变体的表达证实磷酸化影响质膜的定位，并显示较高的Na ⁺S280A和S283D突变体的累积。总体而言，结果表明AtPIP2; 1的C末端结构域中的磷酸化会影响其亚细胞定位和阳离子转运能力。