The unraveling architecture of the junctional sarcoplasmic reticulum.
The sarcoplasmic reticulum (SR) of skeletal muscle controls the contraction-relaxation cycle by raising and lowering the myoplasmic free-Ca2+ concentration. The coupling between excitation, i.e., depolarization of sarcolemma and transverse tubule (TT) and Ca2+ release from the terminal cisternae (TC) of SR takes place at the triad. The triad junction is formed by a specialized region of the TC, the junctional SR, and the TT. The molecular architecture and protein composition of the junctional SR are under active investigation. Since the junctional SR plays a central role in excitation-contraction coupling and Ca2+ release, some of its protein constituents are directly involved in these processes. The biochemical evidence supporting this contention is reviewed in this article.
Volpe
P
P
Department of Physiology, University of Texas, Galveston 77550.
D000818:Animals; D002118:Calcium / Q000502:physiology*; D015220:Calcium Channels / Q000502:physiology; D009119:Muscle Contraction; D012519:Sarcoplasmic Reticulum / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure
D015220:Calcium Channels; D002118:Calcium