Abstract
The uptake of calcium into the sarcoplasmic reticulum (SR) and its subsequent release from the SR play a key role in the regulation of the cytosolic calcium concentration and the excitation-contraction coupling in cardiac muscle. While calcium uptake, catalyzed by the calcium-dependent ATPase, is thought to occur throughout the SR, the release of calcium is controlled by a complex of proteins localized to a distinct region, the junctional SR. This complex consists of the calcium release channel or ryanodine receptor (RyR), the high capacity calcium-binding protein calsequestrin located in the lumen of the junctional SR, and the junctional SR transmembrane proteins triadin 1 and junctin which are hypothesized to anchor calsequestrin to the RyR.
Transgenic mice with cardiac-specific overexpression of triadin1 or junctin show distinct cardiac phenotypes with altered cellular and subcellular morphology, changes in contractile properties and/or in the expression of junctional SR proteins suggesting that these junctional sarcoplasmic reticulum transmembrane proteins are of functional relevance for the regulation of calcium release in the heart.
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Müller, F., Kirchhefer, U., Begrow, F. et al. Junctional sarcoplasmic reticulum transmembrane proteins in the heart. Basic Res Cardiol 97 (Suppl 1), I52–I55 (2002). https://doi.org/10.1007/s003950200030
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DOI: https://doi.org/10.1007/s003950200030