Force generating mechanisms in striated muscle.

Force generation in muscle fibers is generally believed to arise from a structural change in the actomyosin crossbridge. The structure of the low ionic strength crossbridge has been found to be significantly different from that of the rigor crossbridge, which raises the possibility that contractile force may be generated by a transition between these two actomyosin configurations. Another possibility for force generation is based on data suggesting that the length of the subfragment 2 moiety of the myosin molecule may shorten when it moves away from the backbone of the thick filament. Experiments bearing these potential force generating processes are reviewed.