Difference between Actin and Myosin

The main difference between Actin and myosin is on basis of their nature and structure. Actin and myosin are important proteins for eukaryotic cell structure and muscle function. Actin makes thin filaments that help with different cell activities, while myosin forms thick filaments that are important for muscle contraction. Although they have different functions and structures, both proteins are essential for cell growth and movement. They work together to support many biological processes.

Actin VS Myosin

Here are the main differences between actin and myosin.

Character	Actin	Myosin
Definition	Actin is a family of multifunctional cytoplasmic proteins in eukaryotes, that form microfilaments in cytoskeleton, and thin filaments in muscle fibrils.	A superfamily of motor (moveable) proteins that is important for muscle contraction.
Nature	Globular proteins	Motor proteins
Structure	Thin, flexible filaments composed of monomers	Thick filaments with three main parts: head, neck, and tail
Proteins in filaments	Actin, tropomyosin, and troponin	Myosin and meromyosin proteins.
Surface	Smooth	Rough
Function	Provides shape & structure to cell, helps in intracellular transport and muscle contraction	Uses ATP and form force for contraction of muscles
Location	present in muscle fiber, and beneath the cell membrane	Present in muscle cells
Found in	A and I bands of sarcomere.	Only in A bands of sarcomere.
Size	Shorter and thinner (2-2.6 µm length & 0.005 µm diameter).	Longer and thicker (4-5 µm in length & 0.01 µm diameter).
Molecular weight	Less in weight	High in weight
Abundance	More abundant	Less abundant
Cross bridges	Do not form cross bridges	Form cross bridges
Association with ATP	No association with ATP molecules	Associates with ATP
Sliding	Slides into H Zone during muscle contraction	No filament sliding
Muscle Contraction	Interacts with Myosin to support muscle contraction	Initiates muscle contraction by forming a force
End	Actin has one end attached to Z-lines and one free.	Myosin has both ends free, but its heads are linked to ATP for energy.