Name the structure that is NOT involved in excitation-contraction coupling in striated muscle:

Microtubules play no role in excitation-contraction coupling. Action potentials are propagated by the sarcolemma as an essential step in excitation-contraction coupling. Ca++ release from the sarcoplasmic reticulum is necessary for excitation-contraction coupling. The motor end plate is the site of neuromuscular transmission, the first stage of excitation-contraction coupling. T-tubules provide an electrical link whereby action potentials trigger Ca++ release from the sarcoplasmic reticulum.