Actin and Myosin

The human body houses proteins for a variety of activities that it functions and holds a vital role in the body’s normal functioning. There are two major proteins for protein families, namely actin and myosin. Acting refers to the family of multifunctional globular proteins found in eukaryotic cells with a concentration of over 100 micrometres. Myosin use can be defined as a superfamily consisting of motor proteins vital in muscle contraction and other motility processes. This article will provide you with comprehensive knowledge of the differences between myosin and actin.

What is Actin?

Actin refers to a family of multifunctional proteins and forms microfilaments and thin filaments in cytoskeleton and muscle fibrils. Actin is found in all the eukaryotic cells with a concentration of over 100microM, a mass of 42 kDa, and a diameter of 4 to 7 nanometers. Actin protein is further defined as a monomeric subunit consisting of two types of filaments in cells. These two types of filaments are microfilaments. These microfilaments are one of the three major components closed in the cytoskeleton. There are thin filaments also part of the contractile apparatus found in the muscle cells.

Function of Actin

The primary role of actin, is to form linear polymers known as microfilaments that have several functions in a cell structure like migration, replication, and trafficking network. The formation of actin filaments has the nature of the reversible mode, and they often function as depolymerization and rapid polymerization. Microfilaments are also polarised nature materials.

The filament holds distinctness in its two ends, apart from these actin filaments for a group of large-scale networks vital for the successful operation of many functions like:

1. They give mechanical support to cells and help in providing routes to conduct trafficking to help in signal transduction. 

2. Actin filaments also help in the fast assembly and disassembly of actin networks that other functions enable cell migration.

Actin has an abundant presence in cells. Almost 1 to 5% of total protein mass and 10% of muscle cells are made of actin. It is found in both the cell nucleus and cytoplasm. The location is controlled by cell membrane signal transduction pathways that further integrate the stimuli received by cells to restructure actin networks.

What is Myosin?

Myosins can be defined as a superfamily consisting of motor proteins vital for muscle contraction with the wide range of several other motility processes found in eukaryotes. These myosin proteins are ATP-dependent and hold the responsibility of actin-based motility. Myosins are used to describe a group of ATP ases found in smooth muscle tissue cells and striated muscle tissue. Myosin was originally described as a restriction to muscle cells followed by its definition as a large superfamily of protein products that share the properties of ATP hydrolysis, force transduction, and actin-binding. 

Function of Myosin

Myosin performs several important functions due to its composition of head, neck, and tail domains. Some of the important functions of myosin are stated as

1. The head domain of myosin performs the binding of filamentous actin that utilises ATP hydrolysis to generate the force responsible for the movement of filament towards the positive end. 

2. The neck domain of myosin performs the function of linking and lever arm to transducers, a force generated by the catalytic motor domain. This neck do men also serves the purpose of binding for the light chains that can be defined as distinct proteins which further form macromolecular complexes.

3. The tail domain of myosin acts as a mediator of the interaction of cargo molecules and myosin subunits. 

Differences between Actin and Myosin

Conclusion

Actin and myosin are protein fibres for protein families having vital importance for human body functioning. The actin has the role of forming linear polymers known as microfilaments responsible for several functions in a cell structure like migration, replication, and trafficking networks. At the same time, myosin holds the responsibility of binding the filamentous actin and utilising ATP hydrolysis. It performs the function of the transducer for the force generated by the catalytic motor domain. This article has discussed actin and Myosin’s functions to elaborate on the difference between these two protein families present in the eukaryotic part.