运动蛋白质myosin-I在两个步骤中产生其工作冲动
C Veigel1, L M Coluccio, J D Jontes
1Department of Biology, University of York, UK.
Nature
|April 17, 1999
概括
单个myosin-I分子在两个不同的步骤中移动actin,第二步是第二步.
科学领域:
- 生物化学 生化学
- 细胞生物学 细胞生物学
- 生物物理学的生物物理.
背景情况:
- 细胞机动性依赖于运动蛋白质,如肌肉蛋白与actin纤维相互作用.
- 人们认为,肌的力量产生涉及在结合actin后的形状变化.
- 了解这些机械转换是细胞运动的关键.
研究的目的:
- 测量连接到actin的单个myosin头的机械转换.
- 为了研究由肌-I家族成员产生的步进运动.
- 为了描述肌酸氨酸-动氨酸相互作用的动力学和ATP依赖性.
主要方法:
- 使用一个光学子传感器精确测量单个肌肉素头部的运动.
- 研究了大鼠肝脏髓素-I (M(r) 130K) 和的肠道刷边缘髓素-I.
- 在高时间分辨率下检查了快速骨肌肉肌素II的单头子片-1.
主要成果:
- 肌-I蛋白质以两种不同的步骤表现出运动:在10毫秒内进行初始的~6nm步骤,然后在变量延迟后进行~5.5nm步骤.
- 第二阶段后的周期持续时间受ATP度的影响.
- 在高分辨率条件下,第二阶段在快速骨肌肉肌素II中无法检测到.
结论:
- 肌酸-I通过两步的机械过程产生运动.
- 肌-I的较慢的动力学有助于观察不同的机械状态.
- 这提供了对肌肉酶运动蛋白的工作中风机制的洞察.
相关概念视频
01:26Cross-bridge Cycle
As muscle contracts, the overlap between the thin and thick filaments increases, decreasing the length of the sarcomere—the contractile unit of the muscle—using energy in the form of ATP. At the molecular level, this is a cyclic, multistep process that involves binding and hydrolysis of ATP, and movement of actin by myosin.
01:58Mechanical Protein Functions
Proteins perform many mechanical functions in a cell. These proteins can be classified into two general categories- proteins that generate mechanical forces and proteins that are subjected to mechanical forces. Proteins providing mechanical support to the structure of the cell, such as keratin, are subjected to mechanical force, whereas proteins involved in cell movement and transport of molecules across cell membranes, such as an ion pump, are examples of generating mechanical force.
01:15Overview of Myosin Structure and Function
Myosins are a family of molecular motor proteins, first identified in the skeletal muscles, where they are responsible for muscle contraction. Along with their role in muscle contraction, these proteins also play a role in the intracellular transport of molecules and vesicles. There are twenty-four classes of myosins based on their domain sequence and organization. Of the twenty-four, six classes (Myosin I, Myosin II, Myosin V, Myosin VI, Myosin VII, and Myosin X) have been well characterized.
01:16Actin and Myosin in Muscle Contraction
Actin and myosin are contractile proteins that form the sarcomere found in skeletal muscle tissues for regulating muscle contraction. Actin, a globular contractile protein, interacts with myosin for muscle contraction. The skeletal tissue appears striped or striated under a microscope due to the repeated arrangement of contractile proteins actin and myosin along the length of myofibrils. Dark A bands and light I bands repeat along myofibrils, and the alignment of myofibrils in the cell causes...
01:18Role of Myosin in Cell Migration
Myosins are multimeric motor proteins involved in various cellular processes such as migration, adhesion, and proliferation. Myosin II is the most common type in animal cells, which binds and cross-links actin filaments.
Myosin II is a hexamer comprising two heavy chains with globular heads and coiled-coil tails, two regulatory light chains, and two essential light chains. The ATPase sites on the myosin heads hydrolyze ATP, and the released phosphate generates the force for contraction. It is...
Myosin II is a hexamer comprising two heavy chains with globular heads and coiled-coil tails, two regulatory light chains, and two essential light chains. The ATPase sites on the myosin heads hydrolyze ATP, and the released phosphate generates the force for contraction. It is...
01:20Excitation-Contraction Coupling in Skeletal Muscles
Excitation-contraction coupling is a series of events that occur between generating an action potential and initiating a muscle contraction. It occurs at the triad, a structure found in skeletal muscle fibers that comprise a T-tubule and terminal cisternae of the sarcoplasmic reticulum on each side. These triads are visible in longitudinally sectioned muscle fibers. They are typically located at the A-I junction — the junction between the A and I bands of the sarcomere.
When an action potential...
When an action potential...