What Is a Myosin?

Myosin, also known as myosin, is a type of ATP-dependent molecular motor in eukaryotic cells, which plays an important role in cell movement and intracellular material transport. For example, myosin II plays an important role in muscle contraction and cell division. Other types of myosin have similar functions. This protein was initially described as an ATPase that exists in both smooth muscle and striated muscle. Later, after Pollarg and Korn's research on myosin-like function in the genus Acanthopanax, it was discovered that many eukaryotic cells have homologous protein genes. The use of such proteins has been demonstrated not only in muscle cells.

The main component of muscle protein

Regardless of the source of myosin, its basic structure is composed of one or two heavy chains and several light chains. In general, myosin is composed of three domains: the motor domain, the neck, and the tail.

Myosin properties

Myosin belongs to the globulin class. It is insoluble in water and soluble in KCl or NaCl solution of 0.6mol / ml. It has enzymatic activity. It can hydrolyze the terminal phosphate group of ATP by interacting with actin. It can also hydrolyze GTP, CTP, etc., and convert chemical energy into mechanical energy, thereby generating various forms of motion. Physical and chemical studies have shown that the viscosity and flow birefringence of myosin solution are significantly reduced after adding ATP. It was later confirmed that this was caused by the breakdown of the actin and myosin complexes, resulting in two protein molecules with relatively small axes.

Myosin function

As a molecular motor of cytoskeleton, myosin is a multifunctional protein whose main function is to provide force for muscle contraction. The sliding filament theory holds that muscle contraction is the result of the actin filaments and myosin filaments sliding on each other. During muscle contraction, the length of the thick and thin filaments does not change. When the filaments slide, the head of myosin contacts with the molecules of actin, tilts, and finally detaches. A continuous process of detachment, with the result that the filaments slide relative to each other.

Myosin is also widely present in non-muscle cells. It is a component of the cytoskeleton and provides the required force for cytoplasmic flow, organelle movement, material transport, mitosis, cytokinesis, and cell apical growth. Devour, move, fertilize and absorb

Such as physiological processes, it acts as a regulator of different levels of non-muscle cell life activities, from simple intercellular signal transmission to higher-level regulation such as directional migration and changes in cell shape. Studies have shown that myosin is the normal growth and division of Dictyostelium discoideum under shaking culture, surface receptor capping, multicellular development into fruiting bodies, and cell-to-vessel separation Necessary for life activities such as adhesion [6]. Yan Longfei's research in the 1980s showed that myosin may perform important functions in the elongation of pollen tubes of higher plants such as cucumber and the movement of pea leaf tendrils. Kinkema et al. (1994) proved that plant myosin has different physiological functions at different stages and parts of plant growth and development ^[3] .