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Difference Between Actin and Myosin

Difference Between Actin and Myosin: A variety of protein types build up in our human body. Proteins have various activities and play an essential role in the body’s regular functioning—the same as Muscles are made up of a variety of proteins. What we’re here to talk about – Myosin and actin are two protein molecules present in muscles. Actin and Myosin, two protein molecules, are principally responsible for muscle contraction in humans as well as other mammals. Actin and myosin, coupled with protein regulators such as troponin, meromyosin, and tropomyosin, regulate voluntary muscle movements throughout the body. In this article, we are going to discuss what are these proteins and the Difference Between Actin and Myosin.

Difference Between Actin and Myosin

Actin and myosin proteins form filaments that are organized longitudinally in myofibrils. They are also in charge of the both cellular and non-cellular movement. Before jumping into the Difference Between Actin and Myosin, we should must know about antin and mysin individually.

What is Actin?

  • In muscle cells, a collection of protein molecules known as actin comes together to create a thin band.
  • All eukaryotic cells contain actin, which has a concentration of more than 100 microM, a mass of 42 kDa, and a diameter of 4–7 nanometers. The protein that makes up the filament is in charge of constructing the cellular cytoskeleton in eukaryotic cells.
  • The monomeric and polymeric versions, referred to respectively as G-actin and F-actin, are further divided. G-actin is a globular actin protein, whereas F-actin is a filamentous actin protein.
  • In addition, actin protein is described as a monomeric subunit made up of two different filament types in cells. Microfilaments include these two kinds of filaments.

Function – Cell migration, cytokinesis, and skeletal muscle contraction all depend on these bands. They also aid in communication and mobility, and they preserve the shape of the cell.

Difference Between Actin and Myosin -_3.1

What is Myosin?

  • A family of proteins known as “myosin” combine to form tight bands in muscle cells. A superfamily of motor proteins known as myosins is essential for the contraction of muscles.
  • These ATP-dependent myosin proteins are in charge of actin-based motility. A class of ATPases found in the cells of striated and smooth muscle tissue is referred to as myosins.
  • The structure of myosin includes a head, neck, tail, heavy chains, and light chains.
  • Initially, myosin was thought to be a limitation for muscle cells.
  • It refers to a superfamily of protein compounds that have ATP hydrolysis, force transduction, and actin-binding functions in common.

Function – Myosin’s head domain is important for connecting filamentous actin, which uses ATP hydrolysis to produce the force necessary to drive the filament nearer the positive end. Myosin’s neck domain serves as a connection and lever arm for transducers, transferring a force produced by the catalytic motor domain. The connection between cargo molecules and myosin subunits is mediated by the myosin tail domain.

Difference Between Actin and Myosin in Tabular Form

The fundamental distinction between actin and myosin is that actin is a protein that produces tiny contractile filaments within muscle cells. On the other hand, muscle cells produce dense contractile filaments as a result of the protein myosin. For clearer distinction, view the further Difference Between Actin and Myosin in tabular form below.

Difference Between Actin and Myosin
Characteristics Actin Myosin
Definition The majority of eukaryotic cells include actin, a group of globular protein molecules that contributes to the body’s structure, form, and motion. The motor proteins known as myosin and actin are the building blocks of muscle fiber contraction.
Shape creates a brief, slender filament. A lengthy, dense filament of myosin is created.
Present in which Band discovered in bands A and I. discovered in a sarcomere’s A bands.
Size These are smaller in size and thinner. These are larger, longer, and thicker.
striation The striations on actin filaments are thinner. Striations on myosin filaments are dark.
Appearance Tropomyosin and troponin make up this substance. It is made up of meromyosin.
Filaments Compared to myosin, its filaments are more numerous. Actin has more filaments, although it has less filaments.
Surface The actin has a smooth surface. The myosin has a rough surface.
cross-bridges Don’t build any cross-bridges. Make cross-bridges.
End of the Filaments At one end, actin filaments are unattached. At both ends, myosin filaments are unbound.
Locations It can be found in the muscle fibers, cell membrane, cell wall, and microfilaments. It’s in the muscle cells.

Difference Between Actin and Myosin in Points

The two kinds of proteins that produce filaments are myosin and actin. Both of these are found in the muscle cells. Muscle contraction is also aided by the connections and interactions between actin and myosin. They are arranged longitudinally in myofibrils. Here, we offer a few Difference Between Actin and Myosin in points for further clarity.

  • Actin proteins, troponin, and tropomyosin make up the filaments. Meromyosin and myosin make up the filament.
  • The quantity of actin filaments is enormous. There are six actin filaments for every myosin filament.
  • This has a small length and is referred to as the thin filament. This has a larger length and is referred to as the thick filament.
  • The Z-line is attached to one end, which is free on the other.Both ends are unrestricted.

Difference Between Actin and Myosin -_4.1

  • This enables the H-zone to slide into position during muscular contraction. Throughout a muscle contraction, this does not budge.
  • The surfaces of the actin filaments are slick. The surface of the myosin filaments is rough.

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What is the function of actin and myosin?

Actin filaments generate force that causes contractions, such as those seen in muscle contraction, cell motility, and cytokinesis, and myosin motors use this force to transport subcellular organelles and large molecular assemblies along actin filaments.

What is the difference between actin and myosin in sarcomere?

The Z disc, which contains the crosslinking protein -actinin, is connected to the actin filaments at their positive ends. At the M line in the centre of the sarcomere, the myosin filaments are fixed.

How do you remember the difference between actin and myosin?

The difference between actin and myosin can be remembered by these two characteristics -
Ends - The myosin protein has both free ends, whereas the actin protein only has a free end on one side.
Sliding -Actin filaments slide into the H zone during contraction, whereas myosin protein filaments do not slide into the H zone during contraction.

About the Author

Hi buds, I am Monisa, a postgraduate in Human Physiology (specialization in Ergonomics and Occupational health) with 1.5 years of experience in the school education sector. With versatile writing skills, I provide educational content to help students find the right path to success in various domains, such as JEE, NEET, CUET, and other entrance exams.

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