The thin filaments of vertebrate muscle are composed primarily of the globular protein complex troponin, the super-coiled protein tropomyosin and the helical homo-polymer F-actin. Tropomyosin lies approximately along the main helical groove of the F-actin. The regulation of muscle is effected by the binding and unbinding of calcium to troponin molecules which reside on the thin filament. This binding changes the thin-filament structure thus modulating the acto- myosin interaction and the subsequent production of tension. It is this change that Dr. Mendelson plans to study. He hopes ultimately to understand how the change that occurs at the acto-myosin site causes regulation. Neutron scattering and diffraction techniques will be used to study filamentous samples in vitro. Recent advances by him in the deuteration of muscle proteins make the application of this technique to the study of problems of muscle control technically feasible.***//
