Phosphate and ADP Differently Inhibit Coordinated Smooth Muscle Myosin Groups

摘要: Actin filaments propelled in vitro by groups of skeletal muscle myosin motors exhibit distinct phases active sliding or arrest, whose occurrence depends on actin length (L) within a range up to 1.0 μm. Smooth are exponentially distributed with ≈150 nm average in vivo—suggesting relevance the L-dependence group kinetics. Here, we found L-dependent arrest and in motility assays smooth myosin. We perturbed individual kinetics varying, physiological concentrations phosphate (Pi, release associated main power stroke) adenosine diphosphate (ADP, minor mechanical step). Adenosine triphosphate was kept constant at concentration. Increasing [Pi] lowered fraction time for which actively sliding, reflected reduced velocity (ν) motile (fmot, that moving); increasing [ADP] increased while ν fmot. introduced specific Pi ADP effects into our recently developed mathematical model propulsion groups. Simulations matched experimental observations described inhibition At low [ADP], were two chemical states group. Upon increase, probability state decreased; upon increased, but became increasingly similar arrested state.