SUBSTRUCTURE AND CONFIGURATION OF RIBOSOMES ISOLATED FROM MAMMALIAN CELLS
SUBSTRUCTURE AND CONFIGURATION OF RIBOSOMES ISOLATED FROM MAMMALIAN CELLS
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DOI：
10.1016/0022-2836(66)90177-x
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发表时间：
1966-01-01
影响因子：
5.6
通讯作者：
KUFF, EL
中科院分区：
文献类型：
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作者：
SHELTON, E;KUFF, EL
肿瘤性小鼠浆细胞（RPC-20浆细胞瘤）含有代谢活性核糖体，其中一些游离在细胞质中，而另一些则与细胞质膜结合。合成血红蛋白的兔网织红细胞似乎只含有游离核糖体。当肿瘤细胞通过均质化被破坏，兔rettculocytes在适当的培养基中裂解，细胞核和碎片通过离心被除去时，产生的上清液用于制备适合于用电子显微镜检查的制剂。一个频谱的游离核糖体，范围从单体到聚合物含有25至30个单位的大小，可以通过超离心后从连续的蔗糖密度梯度采样。直接从上清液或从梯度底部获得膜结合核糖体。在碳包被的Formvar覆盖的网格上制备的核糖体膜被负染色和正染色。单体核糖体由一个大的，形态稳定的亚基和一个小的亚基，其可变的形态表明结构不稳定或功能的意义。当4 ~ 9个成员的小聚核糖体形成圆形或圆形时，小亚基总是朝向中心，而大聚核糖体的单个成员沿穿过小亚基的轴沿着排列，其形状暗示着扁平的螺旋。提出了一种代谢活性的游离多聚核糖体模型。它由核糖体组成，呈螺旋状排列，小的亚基形成中心核心，大的亚基排列在外围。膜结合的核糖体通过大亚基附着在膜上。
Neoplastic mouse plasma-cells (RPC-20 plasma-cell tumor) contain metabolically active ribosomes, some of which are free in the cytoplasm whereas others are bound to cytoplasmic membranes. Rabbit reticulocytes synthesizing hemoglobin appear to contain only free ribosomes. When tumor cells were disrupted by homogenization and rabbit rettculocytes were lysed in appropriate media and nuclei and debris were removed by centrifugation, the resulting supernantant fluids were used to make preparations suitable for examination with the electron microscope. A spectrum of free ribosomes, ranging in size from monomers to polymers containing 25 to 30 units, could be obtained by sampling from a continuous sucrose density gradient after ultra centrifugation. Membrane-bound ribosomes were obtained either directly from the supernatant fluid or from the bottom of the gradient. Films of the ribosomes prepared on carbon-coated, Formvar-covered grids were negatively and positively stained. The monomeric ribosomes consisted of a large, morphologically stable subunit and a small subunit whose variable morphology suggested structural instability or functional significance. When small polyribosomes of 4 to 9 members formed circles or rosettes, the small subunit was always oriented toward the center, while large polyribosomes, whose individual members were arranged along an axis passing through the small subunit, were disposed in shapes suggestive of flattened helices. A model for the metabolically active, free polyribosome is proposed. It consists of ribosomes arranged in a helix, with the small subunits forming a central core and the large subunits arranged around the periphery. Membrane-bound ribosomes were attached to the membranes by the large subunit.