半合成K+通道中的离子选择性被锁定在导电形态结构中
Francis I Valiyaveetil1, Manuel Leonetti, Tom W Muir
1Laboratories of Molecular Neurobiology and Biophysics and Synthetic Protein Chemistry, Rockefeller University and Howard Hughes Medical Institute, 1230 York Avenue, New York, NY 10021, USA.
Science (New York, N.Y.)
|November 11, 2006
概括
研究人员修改了通道以研究离子选择性. 改变的通道即使与离子保持其导体结构,揭示了这些通道如何区分离子的关键见解.
科学领域:
- 生物化学 生物化学
- 分子生物学分子生物学
- 结构生物学 结构生物学
背景情况:
- 通道对于细胞功能至关重要,可选择性地允许离子 (K+) 通过细胞膜.
- 这些通道内的选择性过器负责区分K+和离子 (Na+).
- 众所周知,选择性过器的结构根据它所结合的离子类型而适应.
研究的目的:
- 调查通道中离子选择性的结构基础.
- 要确定改变通道的组成是否会影响其区分K+和Na+离子的能力.
- 阐明离子竞争在维持通道选择性的作用.
主要方法:
- 用局部导向的突变发生法来合成一种改性通道,其中包含了氨酸的d-enantiomer.
- 采用X射线晶体学来确定修改过的通道的高分辨率结构.
- 进行了离子导电测试,以评估道在不同条件下对K+和Na+的透性.
主要成果:
- 合成的通道,在选择性过器中使用修饰的氨基酸,在Na+和低K+度存在时保持其K+导电形状.
- 修改后的通道在没有K+的情况下显示了Na+导电.
- 在K+的存在下,Na+导电被抑制,这表明对过器的结合部位进行竞争.
结论:
- 通道波器结构对不同离子的适应性是其选择性的基础.
- 这些发现强调了离子竞争在维持选择性波器的功能完整性方面的关键作用.
- 这项研究为生物离子通道中的离子选择性机制提供了新的结构和功能洞察.
相关概念视频
01:19Ion 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...
01:24Non-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.
01:19The 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.
01:26Voltage-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...
01:24Non-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.
01:26Voltage-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...