Divergence in the behaviour of the dihydropyridine receptor in muscle.
The process leading from electrical membrane excitation of skeletal muscle fibres to contraction is a classic example of a rapid cellular activation mechanism. Its initial step is a massive release of Ca2+ from a storage compartment, the sarcoplasmic reticulum (SR), into the myoplasm. Ca2+ release occurs through ryanodine receptors (RyRs), homotetrameric ion channel proteins of an enormous mass (ca 2 3 million Da). In excitation-contraction (EC) coupling the type 1 isoform of the RyR (RyR1) is remotely controlled by plasma membrane voltage. A system of narrow invaginations of the plasma membrane, the transverse tubules (T-system), carries the muscle action potential to specialized regions, the triads, where the membranes of the T-system and the terminal cisternae of the SR are in close apposition.
Department of Cell Physiology, Ruhr University Bochum, D-44780 Bochum, Germany. hans-christoph.luettgau@ruhr-uni-bochum.de
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D000818:Animals; D002118:Calcium / Q000378:metabolism; D020746:Calcium Channels, L-Type / Q000378:metabolism*; D006801:Humans; D008564:Membrane Potentials / Q000502:physiology; D051379:Mice; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D019837:Ryanodine Receptor Calcium Release Channel / Q000235:genetics / Q000378:metabolism; D013552:Swine
D020746:Calcium Channels, L-Type; D019837:Ryanodine Receptor Calcium Release Channel; D002118:Calcium