The junction between the transverse tubules (T-tubules) and the sarcoplasmic reticulum (SR) of skeletal muscle is called the triad. At the triad, dihydropyridine receptors (DHPR's) of the T-tubule serve as voltage sensors in excitation-contraction coupling, while ryanodine receptors (RyR's), the calcium release channels, exist in the membrane of the terminal cisternae of the SR. It is thought that during slow phase depolarization of the T-tubule, a third protein, triadin (MW 95 kDa) transmits electrochemical signals to the SR through direct interaction with both DHPR's and RyR's.
Though its exact role in this signaling process is unclear, triadin has been shown to co-localize with both DHPR and RYR at the junctional face of the terminal cisternae.
cardiac triadin; junctional sarcoplasmic reticulum glycoprotein; TRDN; Triadin; triadin 1; triadin 32 kDa (TRISK 32); triadin 49 kDa (TRISK 49); triadin 95; TRISK