Difference Between Actin and Myosin


Muscles are made up of proteins. Actin and myosin are two protein molecules in muscles and are mainly involved in muscle contraction in humans and animals.

Both actin and myosin function by controlling the voluntary muscular movements within the body, along with the regulatory proteins known as troponin, tropomyosin and meromyosin. Actin and myosin proteins build filaments, which are arranged in the myofibrils in a longitudinal manner. They are also responsible for both cellular movements and non-cellular movements.

The main difference between actin and myosin is that actin is a protein that produces thin contractile filaments within muscle cells. In contrast, myosin is a protein that produces dense contractile filaments within muscle cells.

Also Read: Muscles

Let’s learn about the differences between actin and myosin.

Actin and Myosin – Differences

Size of the Filament
Forms a thin and short filament. Myosin forms a thick and long filament.
Regulatory Proteins
It consists of tropomyosin and troponin. It consists of meromyosin.
Found in A and I bands. Found in A bands of a sarcomere.
Cross Bridges
Do not form cross-bridges. Form cross bridges.
The actin filaments have a smooth surface. The myosin filaments have a rough surface.
Actin filaments are huge in number. One myosin filament happens per six actin filaments.
Actin filaments have lighter striations. Myosin filaments have dark striations.
Slide into the H-zone during contraction. Do not slide during contraction.
Actin filaments are free at one end. Myosin filaments are free at both ends.

This concludes some of the basic differences between Actin and Myosin. Stay tuned to BYJU’S Biology for more differences and other Biology related topics.

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