A functional identification of cardiac junctional sarcoplasmic reticulum.
Junctional sarcoplasmic reticulum (SR) has been identified in microsomes from canine ventricular muscle by the presence of calsequestrin and ryanodine-sensitive Ca2+ release channels. These properties, however, are not common to cardiac cells from all species. Seiler et al (1) have recently described a high Mr polypeptide in canine junctional SR similar to the spanning protein subunits of skeletal muscle triads. We now report the existence of a polypeptide with the same mobility in SR from rabbit ventricular muscle and show that those cardiac membranes can associate with transverse (T-) tubules from rabbit skeletal muscle in K cacodylate medium. We propose that this polypeptide and the reaction with T-tubules be considered as criteria for the identification of cardiac junctional SR.
Brandt
N R
NR
Brunschwig
J P
JP
Lattanzio
F A
FA
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002155:Calsequestrin / Q000032:analysis; D004591:Electrophoresis, Polyacrylamide Gel; D007473:Ion Channels / Q000032:analysis; D008854:Microscopy, Electron; D008970:Molecular Weight; D009206:Myocardium / Q000648:ultrastructure*; D011817:Rabbits; D012433:Ryanodine / Q000032:analysis; D012519:Sarcoplasmic Reticulum / Q000648:ultrastructure*
D002155:Calsequestrin; D007473:Ion Channels; D012433:Ryanodine; D002118:Calcium