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首页> 外文期刊>Journal of Molecular Biology >Three-Dimensional Structure of Vertebrate Muscle Z-Band: The Small-Square Lattice Z-Band in Rat Cardiac Muscle
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Three-Dimensional Structure of Vertebrate Muscle Z-Band: The Small-Square Lattice Z-Band in Rat Cardiac Muscle

机译：椎骨肌肉Z波段的三维结构：大鼠心肌中的小方格Z波段。

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The Z-band in vertebrate striated muscle crosslinks actin filaments of opposite polarity from adjoining sarcomeres and transmits tension along myofibrils during muscular contraction. It is also the location of a number of proteins involved in signalling and myofibrillogenesis; mutations in these proteins lead to myopathies. Understanding the high-resolution structure of the Z-band will help us understand its role in muscle contraction and the role of these proteins in the function of muscle. The appearance of the Z-band in transverse-section electron micrographs typically resembles a small-square lattice or a basketweave appearance. In longitudinal sections, the Z-band width varies more with muscle type than species: slow skeletal and cardiac muscles have wider Z-bands than fast skeletal muscles. As the Z-band is periodic, Fourier methods have previously been used for three-dimensional structural analysis. To cope with variations in the periodic structure of the Z-band, we have used subtomogram averaging of tomograms of rat cardiac muscle in which subtomograms are extracted and compared and similar ones are averaged. We show that the Z-band comprises four to six layers of links, presumably alpha-actinin, linking antiparallel overlapping ends of the actin filaments from the adjoining sarcomeres. The reconstruction shows that the terminal 5-7 nm of the actin filaments within the Z-band is devoid of any alpha-actinin links and is likely to be the location of capping protein CapZ. (C) 2015 The Authors. Published by Elsevier Ltd.
机译：脊椎动物横纹肌中的Z带使相邻肉瘤的极性相反的肌动蛋白丝交联，并在肌肉收缩期间沿肌原纤维传递张力。它也是许多涉及信号传导和肌原纤维形成的蛋白质的位置。这些蛋白质的突变导致肌病。了解Z波段的高分辨率结构将有助于我们了解Z波段在肌肉收缩中的作用以及这些蛋白质在肌肉功能中的作用。在横截面电子显微照片中Z带的外观通常类似于小方格或网状外观。在纵断面中，Z波段的宽度随肌肉类型的变化比物种变化大：慢骨骼和心肌的Z宽度要比快骨骼的宽。由于Z波段是周期性的，因此先前已将Fourier方法用于三维结构分析。为了应对Z波段周期结构的变化，我们使用了大鼠心肌X线断层图的子图平均法，其中提取并比较了子图，并对相似的子图进行了平均。我们显示Z波段包括四到六层的链接，大概是α-肌动蛋白，连接来自相邻肉瘤的肌动蛋白丝的反平行重叠端。重建显示Z带内肌动蛋白丝的5-7 nm末端没有任何α-肌动蛋白连接，很可能是封端蛋白CapZ的位置。 （C）2015作者。由Elsevier Ltd.发布

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