Location of translational initiation factor IF3 on the small ribosomal subunit
Location of translational initiation factor IF3 on the small ribosomal subunit
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DOI：
10.1073/pnas.96.8.4301
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发表时间：
1999-04-13
影响因子：
11.1
通讯作者：
Frank, J
中科院分区：
文献类型：
--
作者：
McCutcheon, JP;Agrawal, RK;Frank, J
用冷冻电子显微镜测定了与嗜热栖热菌（Thermus thermophilus）核糖体30S亚基结合的翻译起始因子IF3的位置。从两个重建计算的差异图显示了三个突出的正密度叶。以前解决的IF3的晶体结构非常适合这些叶中的两个，而第三个叶可能是由IF3结合引起的30S亚基的构象变化引起的。我们的放置IF3的30S亚基允许理解在结构方面的生化功能，这个起始因子，即它的能力，解离70S核糖体成30S和50S亚基和优先选择的起始tRNA IF3在启动过程中。
The location of translational initiation factor IF3 bound to the 30S subunit of the Thermus thermophilus ribosome has been determined by cryoelectron microscopy, Both the 30S IF3 complex and control 30S subunit structures,were determined to 27-Angstrom resolution. The difference map calculated from the two reconstructions reveals three prominent lobes of positive density. The previously solved crystal structure of IF3 fits very well irate two of these lobes, whereas the third lobe probably arises from conformational changes induced in the 30S subunit as a result of IF3 binding. Our placement of IF3 on the 30S subunit allows an understanding in structural terms of the biochemical functions of this initiation factor, namely its ability to dissociate 70S ribosomes into 30S and 50S subunits and the preferential selection of initiator tRNA by IF3 during initiation.