在Na+/K+-ATPase释放离子的过程中,有三个截然不同的和连续的步骤
M Holmgren1, J Wagg, F Bezanilla
1The Marine Biological Laboratory, Woods Hole, Massachusetts 02543, USA. miguel_holmgren@hms.harvard.edu
Nature
|March 8, 2000
概括
- (Na+/K+) 连续释放三个离子. 高速电压跳跃揭示了电荷运动中的三个不同阶段,详细说明了离子释放机制.
科学领域:
- 生物化学 生物化学
- 分子生物学分子生物学
- 膜运输 运输 膜运输
背景情况:
- Na+/K+是一种关键的P型ATPase,参与维持细胞离子梯度.
- 在P型ATPases中的离子封闭和解封机制尚未完全理解.
- 缺乏的Na+/K+活动涉及电致转位步骤.
研究的目的:
- 为了阐明Na+/K+对离子的顺序解封和释放.
- 研究膜电位在调节Na+/K+形态动态中的作用.
- 为了描述离子转移期间的稳定状态前的电荷运动.
主要方法:
- 利用高速电压技术,诱导Na+/K+的结构变化.
- 分析了由于电压扰动而产生的稳定状态前电荷运动.
- 量化充电元件来确定离子释放的数量和顺序.
主要成果:
- 在电压跳跃时观察到前稳态电荷运动中的三个不同的放松阶段.
- 证明这些阶段与三种离子的脱和释放相对应.
- 建立了一个连续的,一个接一个地释放三个离子到细胞外空间的机制.
结论:
- Na+/K+ 可以在一定的顺序下,连续释放离子.
- 高速电生理学提供了对离子运动ATPases的短暂状态的洞察.
- 了解这些机制对于理解细胞离子恒温和功能至关重要.
相关概念视频
Primary Active Transport
In contrast to passive transport, active transport involves a substance being moved through membranes in a direction against its concentration or electrochemical gradient. There are two types of active transport: primary active transport and secondary active transport. Primary active transport utilizes chemical energy from ATP to drive protein pumps that are embedded in the cell membrane. With energy from ATP, the pumps transport ions against their electrochemical gradients—a direction they...
Primary Active Transport
In contrast to passive transport, active transport involves a substance being moved through membranes in a direction against its concentration or electrochemical gradient. There are two types of active transport: primary active transport and secondary active transport. Primary active transport utilizes chemical energy from ATP to drive protein pumps embedded in the cell membrane. With energy from ATP, the pumps transport ions against their electrochemical gradients—a direction they would not...
ATP Energy Storage and Release
ATP is a highly unstable molecule. Unless quickly used to perform work, ATP spontaneously dissociates into ADP and inorganic phosphate (Pi), and the free energy released during this process is lost as heat. The energy released by ATP hydrolysis is used to perform work inside the cell and depends on a strategy called energy coupling. Cells couple the exergonic reaction of ATP hydrolysis with endergonic reactions, allowing them to proceed.
One example of energy coupling using ATP involves a...
One example of energy coupling using ATP involves a...
ATP Driven Pumps II: P-type Pumps
The P-type pumps are a large family of integral membrane transporter ATPases. They are divided into five major types based on substrate specificity, from I to V.
A typical P-type pump has three cytosolic domains: nucleotide-binding (N), phosphorylation (P), and activator (A) domains. These domains are connected to the membrane-spanning helices by short amino acid segments. ATP hydrolysis and covalent phosphoenzyme intermediate formation are crucial parts of the catalytic cycle. At the highly...
A typical P-type pump has three cytosolic domains: nucleotide-binding (N), phosphorylation (P), and activator (A) domains. These domains are connected to the membrane-spanning helices by short amino acid segments. ATP hydrolysis and covalent phosphoenzyme intermediate formation are crucial parts of the catalytic cycle. At the highly...
ATP Energy Storage and Release
ATP is a highly unstable molecule. Unless quickly used to perform work, ATP spontaneously dissociates into ADP and inorganic phosphate (Pi), and the free energy released during this process is lost as heat. The energy released by ATP hydrolysis is used to perform work inside the cell and depends on a strategy called energy coupling. Cells couple the exergonic reaction of ATP hydrolysis with endergonic reactions, allowing them to proceed.
One example of energy coupling using ATP involves a...
One example of energy coupling using ATP involves a...
Primary Active Transport
In contrast to passive transport, active transport involves a substance being moved through membranes in a direction against its concentration or electrochemical gradient. There are two types of active transport: primary active transport and secondary active transport. Primary active transport utilizes chemical energy from ATP to drive protein pumps embedded in the cell membrane. With energy from ATP, the pumps transport ions against their electrochemical gradients—a direction they would not...


