Role of ATP, Power Stroke, Muscle Contraction
Relaxed Muscle, thin filament
Sarcoplasmic reticulum releases Ca2+ into the sacroplasm.
Myosin heads bind to actin
Myosin heads swivel toward center of sarcomere (power stroke)
ATP binds to the myosin head and detaches if from actin
Hydrolysis of ATP transfers energy to myosin head and reorients it.
Contractiion continues if ATP is available and Ca2+ level in the sarcoplasm is high.