一个Na+和K+导电通道的原子结构
Ning Shi1, Sheng Ye, Amer Alam
1Department of Physiology, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9040, USA.
Nature
|February 10, 2006
概括
NaK通道是一个非选择性的阴离子通道,具有独特的结构,与K+通道不同. 它的选择性过架构允许 (Na+) 和 (K+) 离子的导电.
科学领域:
- 结构生物学是结构生物学.
- 生物物理学的生物物理.
- 分子生物学分子生物学
背景情况:
- 离子选择性是离子通道的一个基本特性.
- 虽然K+通道的选择性已被很好地理解,但其他阴离子通道的选择性的结构基础在很大程度上是未知的.
- 四基离子通道具有共同的孔隙结构,但在离子选择机制上有所不同.
研究的目的:
- 为了确定来自Bacillus cereus的NaK通道的晶体结构.
- 阐明NAK通道非选择性的结构基础.
- 为了将NaK通道结构与已知的K+通道进行比较.
主要方法:
- 进行X射线晶体学,以在Na+和K+结合状态下获得NaK通道的结构.
- 高分辨率结构分析 (2.4 Å和2.8 Å).
- 使用86Rb流量试验进行功能分析.
主要成果:
- NaK频道与KcsA K+频道的整体结构相似,但具有独特的选择性过器架构.
- NaK通道的选择性过器保留了两个阴离子结合点 (相当于K+通道点3和4),但有一个前厅,而不是两个结合点 (相当于K+通道点1和2).
- 功能性测试证实,NaK通道能导出Na+和K+离子.
结论:
- NaK通道的选择性波器结构与K+通道的选择性波器结构有很大的不同.
- NaK通道的波器序列类似于循环核酸入通道,表明它们的孔的潜在结构表示.
- 独特的结构解释了该通道能够导出Na+和K+离子的能力.
相关概念视频
Ion Channels
The movement of ions like sodium, potassium, and calcium into and out of the cell is essential to maintain the electrochemical gradient in living cells. The ion channels—a class of membrane transport proteins—help maintain this ionic gradient for the smooth functioning of physiological activities such as maintaining cell size and volume, conducting nerve impulses, and gas and nutrient exchange.
Ion channels are specialized integral membrane proteins on the plasma membrane that allow specific...
Ion channels are specialized integral membrane proteins on the plasma membrane that allow specific...
Non-gated Ion Channels
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.
Compared to the gated ion channels, the non-gated channels, also known as leakage or passive channels, have no gating mechanism.
The Role of Ion Channels in Neuronal Computation
A postsynaptic neuron usually receives numerous impulses from several other presynaptic neurons. The axon hillock of the postsynaptic neuron integrates all these signals and determines the likelihood of firing an action potential.
Sometimes a single EPSP is strong enough to induce an action potential in the postsynaptic neuron. However, multiple presynaptic inputs must often create EPSPs around the same time for the postsynaptic neuron to be sufficiently depolarized to fire an action potential.
Sometimes a single EPSP is strong enough to induce an action potential in the postsynaptic neuron. However, multiple presynaptic inputs must often create EPSPs around the same time for the postsynaptic neuron to be sufficiently depolarized to fire an action potential.
Voltage-gated Ion Channels
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...
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...
Non-gated Ion Channels
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.
Compared to the gated ion channels, the non-gated channels, also known as leakage or passive channels, have no gating mechanism.
Voltage-gated Ion Channels
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...
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...


