Difference Between Actin and Myosin

Introduction

Muscles are made up of proteins. Actin and myosin are two protein molecules present in muscles and are mainly involved in the contraction of the muscle in both 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, whereas myosin is a protein that produces the dense contractile filaments within muscle cells.

Also Read: Muscles

Let’s learn about the differences between actin and myosin

Actin and Myosin – Differences

Actin

Myosin

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.

Location

Found in A and I bands.

Found in A bands of a sarcomere.

Cross Bridges

Do not form cross-bridges.

Form cross bridges.

Surface

The actin filaments have a smooth surface.

The myosin filaments have a rough surface.

Number

Actin filaments are huge in number.

One myosin filament happens per six actin filaments.

Appearance

Actin filaments have lighter striations.

Myosin filaments have dark striations.

Sliding

Slide into H zone during contraction.

Do not slide during contraction.

Ends

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 with BYJU’S Biology for more differences and other Biology related topics.

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