Verschoor A, Frank J, Boublik M
J Ultrastruct Res. 1985 Sep;92(3):180-9. doi: 10.1016/0889-1605(85)90045-x.
In electron micrographs of 50 S (large) subunits from Escherichia coli ribosomes, the highly preferred crown view is inferred to represent the roughly hemispherical particle lying with its flat or concave face against the carbon film. Single particle averaging allows the reproducible details of the crown view particle to be recognized. Multivariate image analysis shows the most variable morphological features of this view to be the two side protrusions, the L7/L12 stalk and the L1 ridge, both of which show apparent positional variations. The invariance of the features of the particle body implies that the movements of the side protrusions are not merely a result of perspective changes produced by major rotations of the particle body out of its quasistable, flat-lying position. A bending point localized on the L7/L12 stalk is conjectured to represent a functional "hinge" that may be related to the secondary/tertiary structure of the L7/L12 dimeric protein.
在大肠杆菌核糖体50S（大亚基）的电子显微照片中，高度优选的冠状视图被推断为代表大致半球形的颗粒，其平坦或凹面靠在碳膜上。单颗粒平均法可识别冠状视图颗粒的可重复细节。多变量图像分析表明，该视图中最可变的形态特征是两个侧面突起、L7/L12柄和L1脊，两者均表现出明显的位置变化。颗粒体特征的不变性意味着侧面突起的运动不仅仅是颗粒体从其准稳定的平躺位置发生大旋转所产生的视角变化的结果。推测位于L7/L12柄上的一个弯曲点代表一个功能性“铰链”，它可能与L7/L12二聚体蛋白的二级/三级结构有关。
