在一个单一负电荷的残留物中定位的内向整化K+通道的门
B A Wible1, M Taglialatela, E Ficker
1Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, Texas 77030.
Nature
|September 15, 1994
概括
内部调整通道 (IRK) 呈现出电压依赖的门. 一个单一的氨基酸变化,M2域中的阿斯巴拉丁酸到阿斯巴拉丁酸,控制了这一关键的门类表型.
科学领域:
- 分子生物学分子生物学
- 生物物理学的生物物理.
- 离子通道功能 离子通道功能
背景情况:
- 内部调整的K+通道 (IRK) 控制离子流的方向.
- IRK封锁涉及电压依赖的Mg2+块和内在封锁机制.
- IRK1和ROMK1表现出明显的Mg2+亲缘关系和封闭性质.
研究的目的:
- 调查IRK通道中电压依赖门的结构基础.
- 确定负责IRK1和ROMK1.1之间差异性门表型的特定氨基酸残留物.
主要方法:
- IRK通道家族成员的大规模和局部定向的突变发生.
- 突变通道结构的电生理学分析.
- 对IRK1和ROMK1门关特性进行比较研究.
主要成果:
- 在IRK1的M2域中,单个氨基酸替代 (D172N) 赋予了ROMK1类门.
- 在ROMK1中发生的逆转基因突变 (N171D) 导致了IRK1类门.
- 这一位置上的负电荷残留物是IRK关门的关键决定因素.
结论:
- 电压依赖的IRK通道封闭是由M2域中的单一氨基酸残留控制的.
- 这种残留物,在IRK1中的阿斯巴酸盐,决定了通道的内在封闭性质.
- 这些发现突出了特定带电残留在离子通道功能和调节中的作用.
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Ion channels are specialized proteins on the plasma membrane that allow charged ions to pass down their electrochemical gradient. Their main function is to maintain the membrane potential which is critical for cell viability. These channels are either gated or non-gated and can transport more than a thousand ions within milliseconds for the cellular event to occur.
Compared to the gated ion channels, the non-gated channels, also known as leakage or passive channels, have no gating mechanism.
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Ligand-gated ion channels are transmembrane proteins that play a vital role in intercellular communication and functions of the nervous system. They allow the influx of ions across the membrane once the neurotransmitter binds, allowing the subsequent transmission of electrical excitation across the neurons. Other ligand-gated ion channels, like the γ-aminobutyric acid (GABA) receptor, permit anions like chloride into the cells on the binding of the GABA molecule. Their entry into the cell...
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Voltage-gated ion channels are transmembrane proteins that open and close in response to changes in the membrane potential. They are present on the membranes of all electrically excitable cells such as neurons, heart, and muscle cells.
Generally, all voltage-gated ion channels have a 'voltage-sensing domain' that spans the lipid bilayer. The charged residues in the sensor move in response to the membrane potential changes that open the channel allowing ions movement. There are several types of...
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