Before revision:  We show further that for processive motors, the time required to build to stall (tbuild) scales with Fmax/(k*Vmax), where Fmax is the ensemble stall force and Vmax is the unloaded gliding velocity of the motor ensemble. Thus, increased environmental stiffnesspromotes faster force-buildup even without the myosin catch-bond, and force production will be limited when tbuild exceeds time scales of force relaxation such as actin turnover. Together, these results reveal how motor filament properties and environmental mechanics shape force production by actomyosin networks .
After revision:  We show further that for processive motors, the time required to build to stall (tbuild) scales with Fmax/(k*Vmax), where Fmax is the ensemble stall force and non-muscle myosin IIA revealed distinct regimes of behavior respectively: (1) large assemblies of fast, low-duty ratio motors rapidly build stable forces over a large range of environmental stiffness, (2) ensembles of slow, high-duty ratio motors serve as high-affinity cross-links with force build-up times that exceed physiological timescales, and (3) small assemblies of low-duty ratio motors operating at intermediate speeds may respond sharply to changes in mechanical context--at low forces or stiffness, they serve as low affinity cross-links but they can transition to effective force production via the positive feedback mechanism described above. These results reveal how motor filament properties and environmental mechanics shape force production by actomyosin networks .