STRUCTURE OF THE ACTIN-MYOSIN COMPLEX AND ITS IMPLICATIONS FOR MUSCLE-CONTRACTION

Muscle contraction consists of a cyclical interaction between myosin a nd actin driven by the concomitant hydrolysis of adenosine triphosphat e (ATP). A model for the rigor complex of F actin and the myosin head was obtained by combining the molecular structures of the individual p roteins with the low-resolution electron density maps of the complex d erived by cryo-electron microscopy and image analysis. The spatial rel ation between the ATP binding pocket on myosin and the major contact a rea on actin suggests a working hypothesis for the crossbridge cycle t hat is consistent with previous independent structural and biochemical studies.