A protein complex composed of actin and myosin; it is the essential contractile substance of muscle fiber, active with MgATP.
- platelet a. the contractile protein of platelets, responsible for clot retraction, platelet aggregation, and release of ADP and other biologic amines essential to platelet function. SYN: thrombosthenin.
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ac·to·my·o·sin .ak-tə-'mī-ə-sən n a viscous contractile complex of actin and myosin concerned together with ATP in muscular contraction
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n.
a protein complex formed in muscle between actin and myosin during the process of contraction. See striated muscle.
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ac·to·my·o·sin (ak″to-miґo-sin) a complex of the proteins actin and myosin occurring in muscle. Cf. actin and myosin. See also myosin ATPase.Medical dictionary. 2011.