myosin

(mī′ŏ-sĭn )

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[ my- + ²-ose + -in ]
A protein present in muscle fibrils and constituting about 45% of total muscle protein. It consists of long chains of polypeptides joined by side chains. Myosin and actin are the contractile proteins in muscle fibers. Myosin catalyzes the removal of the third phosphate from adenosine triphosphate (ATP), thereby releasing the energy needed for contraction.
SEE: sarcomere; SEE: actin

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