Copyright@ The Me Graw-Hill Companies, Ine, Permission requited for reproduction or display. Passage of an action potential along the o Muscle action potential propagated Muscle plasm membrane transverse tubule opens Transverse tubule nearby voltage-gated DHP Lateral sac Ryanodine Sarcoplasmic reticulum calcium channels. the “ ryanodine receptor,” located on the sarcoplasmIc reticulum and eca· released ADP O Cataken up calcium ions released into the 6 to tro 0 oval from troponin cytosol bind to troponin removes blocking acton tropomyosin Thin The calcium-troponin Troponin complex"pulls"tropomyosin 确动 off the myosin-binding site of actin, thus allowing the O Cross-bridge moves ATP) binding of the cross-bridge followed by its flexing to Thick slide the actin filament Excitation-contraction coupling in skeletal musclePassage of an action potential along the transverse tubule opens nearby voltage-gated calcium channels, the “ryanodine receptor,” located on the sarcoplasmic reticulum, and calcium ions released into the cytosol bind to troponin. The calcium-troponin complex “pulls” tropomyosin off the myosin-binding site of actin, thus allowing the binding of the cross-bridge, followed by its flexing to slide the actin filament. Excitation-contraction coupling in skeletal muscle