Matching Pairs Skeletal Muscle ContractionOnline version Match the various steps of a skeletal muscle contraction with the descriptions of that action. by Lindsay Spielman 1 Acetylcholine 2 End Plate Potential 3 Acetylcholinesterase 4 Directly causes cross-bridge detachment 5 Tropomyosin 6 Muscle relaxation 7 Calcium release by the SR 8 Toponin 9 Directly causes cross bridge formation Regulatory protein that covers the myosin-binding sites of the actin. Neurotransmitter released by somatic neurons at the neuromuscular junction. Hydrolysis of ATP to ADP and Pi by the ATPase of the myosin head. ATP attaches to the myosin head. Degrades acetylcholine in the synapse. Calcium binds to this regulatory protein on the thin filaments. Calcium is actively pumped back into the SR. Triggered by depolarization of the t-tubules. Local sarcolemma depolarization of the neuromuscular junction.