Inui M, Kimura Y, Sasaki T, Tada M
Department of Medicine, Osaka University School of Medicine, Japan.
Jpn Circ J. 1990 Sep;54(9):1185-91. doi: 10.1253/jcj.54.1185.
Cardiac sarcoplasmic reticulum (SR) plays a special role in controlling free calcium ions (Ca) in heart muscle cells. Ca stored in the SR is released through the Ca release channels when the sarcolemmal membrane is depolarized, thereby inducing contraction, while Ca is reaccumulated by the Ca pump to induce relaxation. In the latter process, the Ca pump of cardiac SR has a regulatory system by cAMP-dependent phosphorylation of a SR protein, phospholamban. Recently, significant progress has been achieved in understanding the molecular mechanisms of Ca release and uptake and its regulation. The structures of the Ca pump and phospholamban have been defined at molecular levels. A direct interaction between these two proteins was demonstrated. The Ca release channel was identified, and turned out to be the foot structure which in situ connects the SR to the sarcolemma/transverse tubule.
心脏肌浆网（SR）在控制心肌细胞中的游离钙离子（Ca）方面发挥着特殊作用。当肌膜去极化时，储存在SR中的Ca通过Ca释放通道释放，从而诱导收缩，而Ca通过Ca泵重新蓄积以诱导舒张。在后一过程中，心脏SR的Ca泵具有一个调节系统，该系统通过对一种SR蛋白受磷蛋白进行cAMP依赖性磷酸化来实现。最近，在理解Ca释放和摄取及其调节的分子机制方面取得了重大进展。Ca泵和受磷蛋白的结构已在分子水平上得到明确。证实了这两种蛋白质之间存在直接相互作用。Ca释放通道已被鉴定出来，结果发现它就是将SR原位连接到肌膜/横管的足状结构。
