Cloning of a cardiac inward rectifier k^+ channel and its gating mechanisms

心脏内向整流k^通道的克隆及其门控机制

• 批准号: 06670096
• 负责人: ISHII Kuniaki
• 金额: $ 1.34万
• 依托单位: Tohoku University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1994
• 资助国家: 日本
• 起止时间: 1994 至 1995
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-06670096/
• 关键词: cloned k channel; inward rectification; heart; patch clamp; Single channel current

We have isolated a cDNA coding for an inward rectifier K^+ channel (RBHIK1) from rabbit heart. The cloned cDNA encodes a protein of 427 amino acids with two putative transmembrane segments. The primary structure of RBHIK1 is highly homologous to that of IRK1 which is an inward rectifier K^+ channel cloned from mouse macrophage by expression cloning. Howere, there are some amino acid sequence differences observed between RBHIK1 and IRK1 in the segment between the first transmembrane segment and putative pore forming region, which may give rise to some functional differences between RBHIK1 and IRK1. RNA blot analysis revealed the expression of RBHIK1 mRNA (approximate estimated size of 5.5 kb) in various rabbit tissues. There are remarkable differences of the expression of RBHIK1 mRNA between the atrium and ventricle. The highest expression of the mRNA was detected in the ventricle, but no expression was detected in the atrium. The expression pattern is in good agreement with electrophys … More iological findings about the different sizes of native inward rectifier K^+ current in the ventricle and atrium.2. THe RBHIK1 current showed strong inward rectification. The amplitude of RBHIK1 current, like native inward rectifier K^+ current, increased as extracellular K^+ concentration increased and the current was blocked by Ba^<2+> or Cs^+ in a voltage- and time-dependent manner. However, although RBHIK1 was cloned from rabbit heart, unlike native cardiac inward rectifier, it exhibited no substantial outward current and negative slope conductance when expressed in Xenopus cocyte. In patch clamp experiments with 145 mMK^+ in pipette at 20-22ﾟC,the single channel conductance of the RBHIK1 channel was 17.8(]SY.+-.])0.47 pS,and that of the native inward rectifier K^+ channel was 23.5(]SY.+-.])0.29 pS.The currents of subconductance state of 2/3 of the full conductance frequently occurred in recordings of the single RBHIK1 channel. The RBHIK1 channel may be composed of three tetrameric constructs. Less

我们已经从兔心脏中隔离了一个cDNA（rbhik1）。小鼠小鼠，howere，在第一个转换和推定的推定孔形成区域之间存在一些酸序列的rbHik1和irk1在心室中检测到中庭和F的mRNA之间的差异很大RBHIK1电流的整流。rbHik1电流k^+浓度的幅度增加了，并且电压在电压和时间依赖的方式中被BA^<2+>或CS^+阻塞。 ，与心脏向外整流器不同。 0.47 PS，天然内向整流器的K^+通道为23.5（]SY。+ - 。]）0.29 ps。在单个RBHIK1通道的记录中，出现了完整的corlenductance的亚电导状态的电流。三个四聚体构建体

项目成果

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K. Ishii 等人：“心脏内向整流器 K^ 通道的克隆和功能表达”FEBS。

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Y. Sasaki et al.: "Voltage-dependent K^+ channel (Kvi.5) cloned from rabbit heart and facilitation of inactivation of the delayed rectifier current by rat β subunit" FEBS Lett.372. 20-24 (1995)

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