contraction of glycerol-extracted cells in response to adenosine triphosphate ( 53 ) , extraction of actin-like or actomyosin-like proteins from cells other than muscle cells ( 54 ) , and identification of activity resembling that of the actomyosin-adenosine triphosphatase system in a variety of nonmuscle tissues ( 40 , 54 ) are consistent with the idea that portions of the complex , striated muscle contractile system may be present in more primitive contractile machinery .
C0001271
actin
C0026820
contractile