Further, we show that PRC1 crosslinks are compliant and do not substantially resist filament sliding by motor proteins in vitro.
When motor-induced filament sliding diminishes, the actin network structure rapidly and reversibly self-organizes into various assemblies.
The relaxed projecting head, oriented almost as needed for actin attachment, will attach, then release Pi followed by ADP, as the lever arm with a purely axial change in tilt drives ∼10 nm of actin filament sliding on the way to the nucleotide-free limit of its working stroke.
Similarly, α and β denote the corresponding interaction strengths for motor induced filament sliding.
Twirling as generally observed with myosin II involves a left-handed actin filament rotation during filament sliding.
This they might accomplish by detaching and reattaching as the target zone moves toward them during filament sliding.
If filament sliding was possible, the applied torque would impose a left handed rotation to the thin filament, matching the observation in vitro [84].
Generally, one or more weak binding intermediates, referred to as A-states, precede strong binding states, referred to as R-states, which produce filament sliding [2].
Subsequently, the distribution and orientation of attached cross-bridges from these same tomograms suggested that, in the absence of filament sliding, the variably angled cross-bridge attachments become locally stabilized in each target zone [36].
Theoretical analysis of the relative filament sliding induced by active cross-linkers (e.g. motor aggregates) has revealed that contractile stresses can be generated even in bundles lacking a sarcomere structure [12] [14].
