Thin Filament Activation by MyBP-C
Force generation in striated muscle results from myosin cyclically interacting with actin, a process regulated by changes in intracellular calcium and mediated through the actin-associated regulatory proteins, troponin (Tn) and tropomyosin (Tm). Studies suggest that the calcium-dependent movement of Tn-Tm on actin functions as an “on-off” switch, regulating myosin binding to actin. To understand how Tn-Tm regulates myosin binding to actin and the potential sensitizing effects of MyBP-C binding to the thin filament, we study the regulatory process at the molecular level using reconstituted single thin filaments in the in vitro motility assay. Using a new “tightrope” assay developed by Dr. Neil Kad, our labs characterize the mechanism by which MyBP-C sensitizes the native thin filament to calcium.