The Kinetics of Mechanically Coupled Myosins Exhibit Group Size-Dependent Regimes

摘要: Naturally occurring groups of muscle myosin behave differently from individual myosins or small commonly assayed in vitro. Here, we investigate the emergence group behavior with increasing size. Assuming number binding sites (N) is proportional to actin length (L) (N = L/35.5 nm), resolve in vitro motility propelled by skeletal for L = 0.2–3 μm. Three distinct regimes were found: L  1 μm, continuous sliding. We theoretically investigated kinetics mechanical coupling via actin. find rapid sliding steps driven power-stroke cascades supported postpower-stroke myosins, and phases without caused prepower-stroke buildup. The three are explained: N = 8, rare cascades; 15, cascade bursts; 35, cascading. Two saddle-node bifurcations occur N (mono → bi mono-stability), steady states corresponding arrest experimentally measured dependence statistics on L concentration correctly predicted.