Physical Society Colloquium

The mechanisms of muscle myosin motors working in ordered filaments, sarcomeres and cells

Dilson Rassier

Department of Kinesiology and Physical Education
McGill University

Muscle myosin II is a molecular motor that transforms chemical energy into mechanical work. In striated muscles, myosin molecules are ordered in filaments. When attached to actin, myosin filaments amplify nanometer-scale molecular changes into large shortenings of muscle cells. The mechanisms behind the myosin-driven cell shortening and resultant force production are under investigation, and there are several features lacking detailed information. These features include the load-dependence and history-dependence of force production, and emerging properties of myosin motors when working cooperatively in changing conditions. Using new systems developed in our laboratory enabling us to measure forces and actin motility on different levels of analysis (cells, myofibrils and myosin motors), we investigated the details of myosin mechanics. These studies suggest a re-evaluation of some features contained in current models of muscle contraction.