Abstract
Transverse tubules (TTs) are invaginations of the cell membrane of cardiomyocytes that play a critical role in the formation of specialized compartments, called dyads, where excitation-contraction coupling occurs. The dyadic cleft is a restricted space between the TT (where L-type Ca2+ channels are localized) and the sarcoplasmic reticulum (SR; which houses RyR2 [ryanodine receptor]).