The structure of actin and myosin filaments Myosin proteins bind to actin filaments and use ATP hydrolysis to drive contraction and movement, acting as a molecular motor in muscles and nonmuscle cells. (more) myosin protein Written by Kara Rogers Kara Rogers is the senior editor of biomedical sciences at Encyclopædia Britannica, where she oversees a range of content from medicine and genetics to microorganisms. She joined Britannica in 2006 and... Kara Rogers Fact-checked by Britannica Editors Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree.... Britannica Editors Last updated Apr. 3, 2026 •History myosin, any of a group of proteins that plays a central role as a molecular motor in cellular movement and force generation. Myosin proteins are distinct from other molecular motors in having a specialized structural system that converts chemical energy from adenosine triphosphate (ATP) into mechanical work, characterized specifically by a “converter” region and a leverlike arm, which work together to amplify motion and to generate force. Found in nearly all eukaryotic cells, myosin is best...

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