Dictionary
ac•to•my•o•sin
Pronunciation: (ak"tu-mī'u-sin), [key]—
n. Biochem.
a complex protein, consisting of myosin and actin, that is the major constituent of skeletal muscle and is thought to interact with ATP to cause muscle contraction.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.