Myosin and myosin-binding protein C are exquisitely organized into giant filamentous
macromolecular complexes within cardiac muscle sarcomeres, yet these proteins must be
continually replaced to maintain contractile fidelity. The overall hypothesis that myosin
filament structure is dynamic and allows for the stochastic replacement of individual
components was tested in vivo, using a combination of mass spectrometry–and
fluorescence-based proteomic techniques. Adult mice were fed a diet that marked all newly …