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. Author manuscript; available in PMC: 2011 Jul 1.
Published in final edited form as: Exerc Sport Sci Rev. 2010 Jul;38(3):135–142. doi: 10.1097/JES.0b013e3181e3734d

Figure 2.

Figure 2

Skeletal muscle intercellular membrane system and triadic proteins. A. The sarcoplasmic reticulum can be divided into two distinct regions, the junctional sarcoplasmic reticulum (SR) which contains the ryanodine receptors (RyRs) and is the site of calcium (Ca2+) release and a network of longitudinal SR which is enriched in sarcoplasmic/endoplasmic reticulum Ca2+-ATPase (SERCA). In mammalian skeletal muscle the triad, which is composed of a transverse-tubule (t-tubule) abutted on each side by junctional SR is located at the edge of the A band. B. Triadic proteins. For clarity, only one of the four dihydropyridine receptors (DHPRs) that contact the RyR1 is shown. APACC, action-potential activated Ca2+ channel; MG-29, mitsugumin 29 kDa; STIM-1, Stromal interaction molecule 1; TRIC-A, trimeric intracellular cation-selective channel A; HRP, histidine-rich Ca2+ binding protein; JFP-45, junctional face protein 45 kDa. See text for details.