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MembraneEndomembrane systemCell envelopeCell membraneT-tubuleSarcolemma


T-tubules are invaginations of the sarcolemma penetrating into the myocyte interior, forming a highly branched and interconnected network that makes junctions with the sarcoplasmic reticulum. T-tubules are selectively enriched with specific ion channels and proteins crucial in the development of calcium transients necessary in excitation-contraction coupling, thereby facilitating a fast and synchronous contraction across the entire cell volume. T-tubules are unique to striated muscle cells, i.e. skeletal and cardiac muscle cells.


Transverse-axial tubular system
Transverse tubule


› Cellular component

Gene Ontology


T-tubule [ GO:0030315 ]
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