The Na+/H+ exchanger as a proton regulatory system : its molecular structure and transport mechanism

Na /H交换剂作为质子调节系统：其分子结构和传输机制

• 批准号: 14580664
• 负责人: WAKABAYASHI Shigeo
• 金额: $ 2.3万
• 依托单位: National Cardiovascular Center Research Institute
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2002
• 资助国家: 日本
• 起止时间: 2002 至 2003
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-14580664/
• 关键词: Na^+; H^+ antiporter; Intracellular pH; Protein Crystal structure; Bioengineering; Biophysics; Nano-machine; Bio-molecule; Protein; Na+; H+アンチポータ

The Na^+/H^+ exchanger (NHEs, SLC9 family) are electroneutral transporters that catalyze the exchange of Na^+ and H^+ in plasma membranes or other intracellular organellar membranes in various animal species. We discovered that calcineurin B homologous protein (CHP, its ubiquitous isoform CHP1) functions as an essential cofactor to support the physiological activity by interacting with the juxtamembrane domain of the plasma membrane-type exchanger isoforms NHE1-5. Furthermore, another isoform CHP2 becomes expressed when cells are malignantly transformed and plays a role in maintaining high intracellular pH in cancer cells. We also analyzed the role of Ca^<2+>-binding sites of CHP and concluded that two Ca^<2+> ions remain to be bound to EF-hand binding sites of CHP when interacts with NHE1 in cell membranes and play an important role in maintaining the physiological function of NHE1.In addition to H^+-transport site, H^+-regulatory site have been recognized to be important for pH regulation by NHE1. We discovered such additional H^+-binding sites in NHE1 by measuring the reverse mode reaction of NHE1 (^<22>Na^+ efflux from the cells). We also identified critical amino acid residues (Arg440, Gly455, Gly456) in NHE1 important for regulation of pH-sensor.

Na^+/h^+交换器（nhes，slc9家族）是电反转运蛋白，可在各种动物物种中催化质膜或其他细胞内细胞器膜中Na^+和H^+的交换。我们发现，钙调神经酶B同源蛋白（CHP，无处不在的同工型CHP1）通过与质膜型交换器的近膜结构域相互作用来支持生理活性的必不可少的辅助因子。此外，当细胞发生恶性转化并在癌细胞中保持高细胞内pH中起作用时，另一个同工型CHP2表达。我们还分析了CHP的Ca^<2+> - 结合位点的作用，并得出结论，当与细胞膜中的NHE1相互作用并发挥作用时，两个Ca^<2+>离子仍待与CHP的EF手工结合位点结合。在H^+运输部位，H^+ - 调节部位维持NHE1的生理功能方面的重要作用已被认为对NHE1的pH调节很重要。我们通过测量NHE1的反向模式反应（^<22> na^+外排的反向模式反应）在NHE1中发现了这种其他H^+ - 结合位点。我们还确定了NHE1中的关键氨基酸残基（Arg440，Gly455，Gly456）对于调节pH传感器的调节很重要。

项目成果

Pang, T., et al.: "Role of Calcineurin B Homologous Protein in pH Regulation by the Na^+/H^+ Exchanger 1 : Tightly Bound Ca^<2+> Ions as Important Structural Elements."Biochemistry. 43(12). 3628-3636 (2004)

Pang, T., et al.：“钙调神经磷酸酶 B 同源蛋白在 Na^ /H^ 交换器 1 的 pH 调节中的作用：紧密结合的 Ca^<2> 离子作为重要的结构元素。”生物化学。

Pang, T., Wakabayashi, S., Shigekawa, M.: "Expression of Calcineuin B Homologous Protein 2 Protects Serum Deprivaion-Induced Cell Death by Serum-Independent Activation of Na^+/H^+ exchanger."J.Biol.Chem.. 277. 43771-4377 (2002)

Pang, T.、Wakabayashi, S.、Shigekawa, M.：“钙调蛋白 B 同源蛋白 2 的表达通过 Na^ /H^ 交换器的血清独立激活来保护血清剥夺诱导的细胞死亡。”J.Biol.Chem。

若林繁夫ほか: "Na^+/H^+交換輸送体:生体プロトン環境を制御するイオントランスポータ"Otology Japan. (印刷中). (2004)

Shigeo Wakabayashi 等人：“Na^+/H^+ 交换转运蛋白：控制生物质子环境的离子转运蛋白”Otology Japan（出版中）。

若林繁夫ほか: "Na^+/H^+交換輸送体の構造と機能-活性に必須な因子としてのCHP"心臓. 34. 333-340 (2002)

Shigeo Wakabayashi 等人：“Na^+/H^+ 交换转运蛋白的结构和功能 - CHP 作为活性的重要因素”Heart. 34. 333-340 (2002)

S.Wakabayashi, et al.: "Two Fundamental Regulatory Factors of the Na^+/H^+ Exchangers : The Proton and CHP In "The Sodium-Hydrogen Exchange, From Molecule to its Role in Disease""Kluwer Academic Publishers. (2003)

S.Wakabayashi 等人：“Na^ /H^ 交换器的两个基本调节因素：质子和 CHP 在“钠-氢交换，从分子到其在疾病中的作用”中”Kluwer 学术出版社。