Preparation and morphology of sarcoplasmic reticulum terminal cisternae from rabbit skeletal muscle.
Preparation and morphology of sarcoplasmic reticulum terminal cisternae from rabbit skeletal muscle.
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DOI：
10.1083/jcb.99.3.875
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发表时间：
1984-09
期刊：
影响因子：
--
通讯作者：
Fleischer S
中科院分区：
文献类型：
--
作者：
Saito A;Seiler S;Chu A;Fleischer S
我们已经开发了一个程序，从骨骼肌，丰富的肌浆网（SR），保留形态完整的交界处的“脚”结构类似于原位观察到的终端池隔离。该馏分是在很大程度上缺乏横小管，质膜，线粒体，三合会（横小管交界处与终端池），和纵向池，如代表性样品的薄切片电子显微镜所示。终端脑池囊泡具有独特的形态特征，不同的孤立的纵向脑池（轻SR）从相同的梯度。终池由两种不同类型的膜组成，即，连接面膜和含Ca ~（2+）泵蛋白的膜，而纵向池仅含含Ca ~（2+）泵蛋白的膜。终池的交界面膜含有足结构，从膜表面延伸约12 nm，并可以通过使用单宁酸增强，负染色和冷冻断裂电子显微镜在薄切片中清晰可见。切向和相交的交界面的平面的终端池的部分，揭示了交替的，方形的脚结构和空间，每个20纳米的正方形的棋盘格状晶格。结构特征的Ca 2+泵蛋白之间的脚在交界面膜，无论是在薄切片或负染色，即使观察到的Ca 2+泵蛋白的nonjunctional膜上的其余部分相同的囊泡。同样地，冷冻断裂复制品揭示了P面的区域含有绳状股，而不是高密度的7-8-nm颗粒可与Ca 2+泵蛋白结合。囊内的内容物的终端池，主要是钙离子结合蛋白（calsequestrin），是有组织的形式股，有时出现paracrycrystalline，并附于内面的膜附近的交界脚。末端脑池制备物与先前描述的重SR组分的不同之处在于其含有最高百分比的结合面膜，具有形态学上保存良好的结合足结构。
We have developed a procedure to isolate, from skeletal muscle, enriched terminal cisternae of sarcoplasmic reticulum (SR), which retain morphologically intact junctional "feet" structures similar to those observed in situ. The fraction is largely devoid of transverse tubule, plasma membrane, mitochondria, triads (transverse tubules junctionally associated with terminal cisternae), and longitudinal cisternae, as shown by thin-section electron microscopy of representative samples. The terminal cisternae vesicles have distinctive morphological characteristics that differ from the isolated longitudinal cisternae (light SR) obtained from the same gradient. The terminal cisternae consist of two distinct types of membranes, i.e., the junctional face membrane and the Ca2+ pump protein-containing membrane, whereas the longitudinal cisternae contain only the Ca2+ pump protein-containing membrane. The junctional face membrane of the terminal cisternae contains feet structures that extend approximately 12 nm from the membrane surface and can be clearly visualized in thin section through using tannic acid enhancement, by negative staining and by freeze-fracture electron microscopy. Sections of the terminal cisternae, cut tangential to and intersecting the plane of the junctional face, reveal a checkerboardlike lattice of alternating, square-shaped feet structures and spaces each 20 nm square. Structures characteristic of the Ca2+ pump protein are not observed between the feet at the junctional face membrane, either in thin section or by negative staining, even though the Ca2+ pump protein is observed in the nonjunctional membrane on the remainder of the same vesicle. Likewise, freeze-fracture replicas reveal regions of the P face containing ropelike strands instead of the high density of the 7-8-nm particles referable to the Ca2+ pump protein. The intravesicular content of the terminal cisternae, mostly Ca2+-binding protein (calsequestrin), is organized in the form of strands, sometimes appearing paracrystalline, and attached to the inner face of the membrane in the vicinity of the junctional feet. The terminal cisternae preparation is distinct from previously described heavy SR fractions in that it contains the highest percentage of junctional face membrane with morphologically well- preserved junctional feet structures.