Human CLC-K Channels Require Palmitoylation of Their Accessory Subunit Barttin to Be Functional*
Human CLC-K Channels Require Palmitoylation of Their Accessory Subunit Barttin to Be Functional*
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人类 CLC-K 通道需要对其辅助亚基 Barttin 进行棕榈酰化才能发挥功能*
DOI：
10.1074/jbc.m114.631705
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发表时间：
2015
期刊：
影响因子：
--
通讯作者：
M. Fischer
中科院分区：
文献类型：
--
作者：
K. Steinke;Nataliya Gorinski;Daniel Wojciechowski;V. Todorov;D. Guseva;E. Ponimaskin;C. Fahlke;M. Fischer
背景：CLC-K通道及其亚基barttin对尿浓度和听力至关重要。结果：非棕榈酰化的barttin突变体降低CLC-K电流幅度而不改变单一通道特性。结论：barttin的棕榈酰化可使CLC-K通道进入激活状态。重要性：预先插入上皮细胞质膜的CLC-K/barttin通道的棕榈酰化/去棕榈酰化可能调节肾氯吸收。CLC-K/barttin氯化物通道对于Henle袢中的NaCl重吸收和内耳中血管纹的钾分泌是必需的。在这里，我们通过其辅助亚基barttin的棕榈酰化研究了此类通道的翻译后修饰。我们发现barttin在体内和体外都被棕榈酰化，并在54和56位确定了两个保守的半胱氨酸残基作为棕榈酰化位点。这两个残基的点突变降低了表达CLC-K/barttin通道的细胞中的宏观电流幅度，与棕榈酰化barttin的相对降低成比例。CLC-K/barttin表达、质膜插入和单通道特性不受影响，表明这些突变减少了活性通道的数量。R8 W和G47 R是在Bartter综合征IV型患者中发现的两种天然存在的barttin突变，可降低barttin棕榈酰化和CLC-K/barttin通道活性。因此，辅助亚基barttin的棕榈酰化可能在Bartter综合征的某些变体中的氯通道功能障碍中发挥作用。我们没有观察到显着的改变barttin棕榈酰化后增加盐和水的摄入量或水分剥夺，表明这种翻译后修饰并不有助于长期适应可变的水分摄入量。我们的研究结果确定Barttin棕榈酰化作为一种新的翻译后修饰CLC-K/Barttin氯通道。
Background: CLC-K channels and their subunit barttin are crucial for urinary concentration and hearing. Results: Non-palmitoylated barttin mutants reduce CLC-K current amplitudes without modifying unitary channel properties. Conclusion: Palmitoylation of barttin switches CLC-K channels into an active state. Significance: Palmitoylation/depalmitoylation of CLC-K/barttin channels pre-inserted in epithelial plasma membranes might regulate renal chloride absorption. CLC-K/barttin chloride channels are essential for NaCl re-absorption in Henle's loop and for potassium secretion by the stria vascularis in the inner ear. Here, we studied the posttranslational modification of such channels by palmitoylation of their accessory subunit barttin. We found that barttin is palmitoylated in vivo and in vitro and identified two conserved cysteine residues at positions 54 and 56 as palmitoylation sites. Point mutations at these two residues reduce the macroscopic current amplitudes in cells expressing CLC-K/barttin channels proportionally to the relative reduction in palmitoylated barttin. CLC-K/barttin expression, plasma membrane insertion, and single channel properties remain unaffected, indicating that these mutations decrease the number of active channels. R8W and G47R, two naturally occurring barttin mutations identified in patients with Bartter syndrome type IV, reduce barttin palmitoylation and CLC-K/barttin channel activity. Palmitoylation of the accessory subunit barttin might thus play a role in chloride channel dysfunction in certain variants of Bartter syndrome. We did not observe pronounced alteration of barttin palmitoylation upon increased salt and water intake or water deprivation, indicating that this posttranslational modification does not contribute to long term adaptation to variable water intake. Our results identify barttin palmitoylation as a novel posttranslational modification of CLC-K/barttin chloride channels.
影响因子：
4
作者：
Davda D;El Azzouny MA;Tom CT;Hernandez JL;Majmudar JD;Kennedy RT;Martin BR
通讯作者：
Martin BR
DOI：
10.1073/pnas.95.8.4690
发表时间：
1998-04-14
影响因子：
11.1
作者：
Qin, N;Platano, D;Birnbaumer, L
通讯作者：
Birnbaumer, L
影响因子：
64.5
作者：
Rocks, Oliver;Gerauer, Marc;Bastiaens, Philippe I. H.
通讯作者：
Bastiaens, Philippe I. H.