肌酸I可以作为一个分子力传感器
Joseph M Laakso1, John H Lewis, Henry Shuman
1Pennsylvania Muscle Institute and Department of Physiology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA.
Science (New York, N.Y.)
|July 5, 2008
概括
肌蛋白I是一种运动蛋白质,作为一个分子力传感器,通过响应细胞张力而大幅改变其运动来起作用. 这种张力敏感性对于各种细胞功能至关重要.
科学领域:
- 细胞生物学 细胞生物学
- 生物物理学的生物物理.
- 分子电机分子电机
背景情况:
- 听力和膜运输等细胞过程依赖于感知分子张力.
- 肌蛋白 I 是一种运动蛋白质,参与这些依赖张力的细胞功能.
研究的目的:
- 为了研究氨酸I的运动性质如何在变化的分子张力下发生变化.
- 为了确定myosin I是否作为分子力传感器起作用.
主要方法:
- 使用光学陷来测量单个肌肉素I分子的位移.
- 在不同的张力水平下,确定了myosin I的actin附着动力学.
主要成果:
- 在2皮克纽顿或更低的张力下,肌蛋白I从动蛋白中分离的速度降低了75倍以上.
- 在电机的电压下,Myosin I从低功率比 (<0.2) 转变为高功率比 (>0.9).
结论:
- 肌I具有显著的张力灵敏度,作为分子力传感器.
- 这种特性支持myosin I在需要力检测的细胞过程中的作用.
相关概念视频
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...
01:58Mechanical 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.
01:08The Sarcomere
A sarcomere is a microscopic segment repeating in a myofibril. The sarcomere fundamentally consists of two main myofilaments: thick filaments called myosin and thin filaments called actin. These filaments interact by sliding past each other in response to stimulus. In addition to myosin and actin, several other proteins, such as tropomyosin, troponin, titin, nebulin, myomesin, α-actinin, and dystrophin, play crucial roles in regulating, structuring, and functioning of the sarcomere.
Each myosin...
Each myosin...
01:10The Role of Actin and Myosin in Non-muscle Cells
Actin and myosin or actomyosin filaments also play a significant role in cells other than those involved in muscle contraction (which occurs within the sarcomere of muscle cells). The mechanism of non-muscle cell contractile bundles was first observed in Dictyostelium and Acanthamoeba. In non-muscle cells, two bundles are commonly found: stress fibers and actomyosin adherence belts. These contractile bundles are smaller and less organized than the ones found in muscle cells. They are held...