The Center for Research in Biological Systems, University of California San Diego, La Jolla, CA 92093, USA.
J Mol Cell Cardiol. 2013 May;58:5-12. doi: 10.1016/j.yjmcc.2012.11.009. Epub 2012 Nov 29.
Advances in microscopic imaging technologies and associated computational methods now allow descriptions of cellular anatomy to go beyond 2-dimensions, revealing new micro-domain dynamics at unprecedented resolutions. In cardiomyocytes, electron microscopy (EM) first described junctional membrane complexes between the sarcolemma and sarcoplasmic reticulum over a half-century ago. Since then, 3-dimensional EM technologies such as electron tomography have become successful in determining the realistic nano-geometry of membrane junctions (dyads and peripheral junctions) and associated structures such as transverse tubules (T-tubules, aka. T-system). Concomitantly, super-resolution light microscopy has gone beyond the diffraction-limit to determine the distribution of molecules, such as ryanodine receptors, with 10(-8) meter (10nm) order accuracy. This review provides the current structural perspective and functional interpretation of membrane junction complexes, which are the central machinery controlling cardiac excitation-contraction coupling via calcium signaling.
微观成像技术的进步和相关计算方法的发展，现在可以让细胞解剖结构的描述超越二维，以空前的分辨率揭示新的微观领域动态。在心肌细胞中，电子显微镜（EM）在半个多世纪前首次描述了肌膜和肌浆网之间的连接膜复合物。从那时起，电子断层扫描等三维 EM 技术已经成功地确定了膜连接（二联体和周边连接）和相关结构（如横管（T 管，又名 T 系统））的真实纳米几何形状。与此同时，超分辨率荧光显微镜已经超越了衍射极限，可以确定 10^(-8) 米（10nm）量级精度的分子（如兰尼碱受体）的分布。这篇综述提供了目前关于膜连接复合物的结构视角和功能解释，这些复合物是通过钙信号控制心脏兴奋-收缩偶联的核心机制。
