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: 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. 39.14 ). 1. A voltage-sensitive calcium channel (see Chapter 16) senses action potentials in the T tubule. These channels are called dihydropyridine (DHP) receptors, owing to their affinity for this class of drugs. The actual Ca 2+ channel of DHP receptors is not essential for skeletal muscle contraction, as external Ca 2+ is not required for contraction in the short term.