Junctional sarcoplasmic reticulum transmembrane proteins in the heart.
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 triadin 1 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.
Müller
Frank U
FU
Institut für Pharmakologie und Toxikologie, Universitätsklinikum Münster, Domagkstr. 12, 48149 Münster, Germany.
Kirchhefer
Uwe
U
Begrow
Frank
F
Reinke
Uta
U
Neumann
Joachim
J
Schmitz
Wilhelm
W
D000818:Animals; D002135:Calcium-Binding Proteins; D002352:Carrier Proteins / Q000378:metabolism*; D008565:Membrane Proteins; D006899:Mixed Function Oxygenases; D009124:Muscle Proteins / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism*; D012519:Sarcoplasmic Reticulum / Q000378:metabolism*
D002135:Calcium-Binding Proteins; D002352:Carrier Proteins; D008565:Membrane Proteins; D009124:Muscle Proteins; C498269:TRDN protein, human; C070048:triadin; D006899:Mixed Function Oxygenases