Molecular aspects of the excitation-contraction coupling in skeletal muscle

Extremely rapid and massive release of Ca2+ from the sarcoplasmic reticulum upon depolarization of the T-tubule regulates the contraction of skeletal muscle. The dihydropyridine receptor (voltage sensor) on the T-tubule faces the ryanodine receptor (Ca2+ release channel) on the sarcoplasmic reticulum at the triadic junction and their intermolecular interaction is responsible for the swift release of Ca2+ from the sarcoplasmic reticulum. We are now beginning to gain insight into the molecular structures that are important for the coupling mechanism.