Actin vs. Myosin — What's the Difference?

Actin is a family of globular multi-functional proteins that form microfilaments in the cytoskeleton, and the thin filaments in muscle fibrils. It is found in essentially all eukaryotic cells, where it may be present at a concentration of over 100 μM; its mass is roughly 42-kDa, with a diameter of 4 to 7 nm.

Myosins () are a superfamily of motor proteins best known for their roles in muscle contraction and in a wide range of other motility processes in eukaryotes. They are ATP-dependent and responsible for actin-based motility.

A protein that forms the microfilaments of the eukaryotic cytoskeleton and plays an important role in cell movement, shape, and internal organization. In muscle cells, it functions with myosin to produce contraction.

Any of a class of proteins that bind with actin filaments and generate many kinds of cell movement, especially the contraction of myofibrils in muscle cells.

A globular structural protein that polymerizes in a helical fashion to form an actin filament (or microfilament).

(biochemistry) Any of a large family of motor proteins found in eukaryotic tissues, allowing mobility in muscles.

One of the six isoforms of actin.

An albuminous body present in dead muscle formed in the process of coagulation which takes place in rigor mortis.

One of the proteins into which actomyosin can be split; can exist in either a globular or a fibrous form

A protein present in muscle, serving as the principle contractile protein in muscle contraction.

The commonest protein in muscle; a globulin that combines with actin to form actomyosin