Title: T-Tubule - an overview | ScienceDirect Topics
Headings: T-Tubule
T-Tubule
Ion Channel Trafficking
T-Tubules
Skeletal Muscle
T-tubules Are Surface Invaginations; the SR Is an Internal Membrane System
Structure and Function of Calcium Release Channels
2 T Tubules and CRUs Revert to More Primitive Forms Under Pathological Conditions
Muscles
Coupling Action Potentials to Contraction
The Cellular Basis of Cardiac Contractility
The SR Releases Stored Ca 2+ to Activate Contraction
Disorders of Muscle Excitability
Calcium couples muscle membrane excitation to filament contraction
Muscle physiology
Excitation–contraction coupling
EXERCISE | Muscle
Voltage-dependent Sarcoplasmic Reticulum Ca 2+ Release

Content: Inside the muscle cell, T tubules interact extensively with the smooth endoplasmic reticulum (SER) surrounding each myofibril. Historically, this SER was called sarcoplasmic reticulum. Terminal cisternae of SER are closely associated with T tubules at foot processes that can be visualized by electron microscopy. Together, T tubules and SER constitute a signal-transducing apparatus that converts depolarizations of the plasma membrane into a spike of cytoplasmic Ca 2+ to trigger contraction ( Fig. 39.14 ). An action potential moving through a T tubule triggers the release of Ca 2+ from SER into the cytoplasm ( Fig. 39.14 ). Ca 2+ binding to troponin allows myosin to interact with the thin filament, initiating contraction. This signal transduction process is called excitation–contraction coupling. Three transmembrane proteins located in the T tubule and the terminal cisternae of the SER cooperate to generate the transient Ca 2+ signal ( Fig.