Molecular Mechanism of Inward Rectifier Potassium Channel 2.3 Regulation by Tax-Interacting Protein-1
Molecular Mechanism of Inward Rectifier Potassium Channel 2.3 Regulation by Tax-Interacting Protein-1
复制标题
内向整流钾通道的分子机制 2.3 Tax-Interaction Protein-1的调控
DOI：
10.1016/j.jmb.2009.07.060
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发表时间：
2009-10-02
影响因子：
5.6
通讯作者：
Long, Jiafu
中科院分区：
文献类型：
--
作者：
Yan, Xiaojie;Zhou, Hao;Long, Jiafu
抑制整流钾通道2.3（Kir2.3）特异性靶向于上皮细胞和神经元细胞的基底外侧膜，因此在维持钾稳态中起重要作用。Tax-interacting protein-1（TIP-1）是一种非典型的含PDZ结构域的蛋白质，其以高亲和力结合Kir2.3，导致Kir2.3在培养的上皮细胞中的细胞内积累。然而，TIP-1/Kir2.3相互作用的分子基础仍然知之甚少。在这里，我们呈现了TIP-1与C-末端Kir2.3-肽（残基436-445）复合的晶体结构，以揭示它们之间相互作用的分子细节。此外，等温滴定量热法实验表明，C-末端Kir2.3-肽与TIP-1的结合比与哺乳动物Lin-7的结合强得多，表明TIP-1可以与哺乳动物Lin-7竞争以将Kir2.3从其基底外侧膜锚定复合物中解偶联。我们进一步表明，C-末端Kir2.3 PDZ结合基序RRESAI内Ser 443的磷酸化/去磷酸化动态调节异源HEK 293 T细胞中Kir2.3/TIP-1的关联。这些数据表明，TIP-I可能作为一个重要的调节器Kir2.3的内吞途径。(C)2009爱思唯尔有限公司保留所有权利。
Inwardly rectifying potassium channel 2.3 (Kir2.3) is specifically targeted on the basolateral membranes of epithelial and neuronal cells, and it thus plays an important role in maintaining potassium homeostasis. Tax-interacting protein-1 (TIP-1), an atypical PDZ-domain-containing protein, binds to Kir2.3 with a high affinity, causing the intracellular accumulation of Kir2.3 in cultured epithelial cells. However, the molecular basis of the TIP-1/Kir2.3 interaction is still poorly understood. Here, we present the crystal structure of TIP-1 in complex with the C-terminal Kir2.3-peptide (residues 436-445) to reveal the molecular details of the interaction between them. Moreover, isothermal titration calorimetry experiments show that the C-terminal Kir2.3-peptide binds much more strongly to TIP-1 than to mammalian Lin-7, indicating that TIP-1 can compete with mammalian Lin-7 to uncouple Kir2.3 from its basolateral membrane anchoring complex. We further show that the phosphorylation/dephosphorylation of Ser443 within the C-terminal Kir2.3 PDZ-binding motif RRESAI dynamically regulates the Kir2.3/TIP-1 association in heterologous HEK293T cells. These data suggest that TIP-I may act as an important regulator for the endocytic pathway of Kir2.3. (C) 2009 Elsevier Ltd. All rights reserved.