据发表于10月16日Science杂志的一篇研究报告，剑桥大学分子生物学实验室由Venki Ramakrishnan主持的研究小组首次获得核糖体与延伸因子(elongation factor G,EF-G)结合的图片。
EF-G是一种参与蛋白质生物合成中多肽链延伸过程的移位酶。研究人员对一种采集自海底火山口的耐热菌的核糖体进行研究，他们将核糖体进行纯化，然后加入一种聚合物，该聚合物能够使多个核糖体线性连接并形成晶体结构，此外研究人员还加入一种名为夫西地酸(fusidic acid)的抗生素，该抗生素能使EF-G连接到核糖体上。
之前研究人员试图使EF-G与核糖体一起进行结晶，但结果出现EF-G被其他核糖体取代下来。据Dunham介绍，之后研究人员对核糖体进行部分切割后，才使EF-G结合到核糖体上。
研究人员利用X射线分析了核糖体与EF-G结合形成的晶体，并通过X射线数据研究该晶体的结构。Dunham在该研究报告中描述了EF-G与核糖体相互作用的详细过程。此外，该报告还对研究核糖体与其他类似于EF-G的蛋白之间的相互作用提供了新信息。（生物谷Bioon.com）
生物谷推荐原始出处：
Science October 15, 2009 DOI: 10.1126/science.1179709
The Structure of the Ribosome with Elongation Factor G Trapped in the Posttranslocational State
Yong-Gui Gao 1, Maria Selmer 2, Christine M. Dunham 3, Albert Weixlbaumer 4, Ann C. Kelley 1, V. Ramakrishnan 1*
1 MRC Laboratory of Molecular Biology, Hills Road, Cambridge, CB2 0QH, UK.
2 MRC Laboratory of Molecular Biology, Hills Road, Cambridge, CB2 0QH, UK.; Present address: Department of Cell and Molecular Biology, Uppsala University, Box 596, Uppsala, SE 751 24, Sweden.
3 MRC Laboratory of Molecular Biology, Hills Road, Cambridge, CB2 0QH, UK.; Present address: Department of Biochemistry, Emory University School of Medicine, Atlanta GA 30322, USA.
4 MRC Laboratory of Molecular Biology, Hills Road, Cambridge, CB2 0QH, UK.; Present address: The Rockefeller University, Box 224, New York NY 10065, USA.
* To whom correspondence should be addressed.
Elongation factor G (EF-G) is a guanosine triphosphatase (GTPase) that plays a crucial role in the translocation of transfer RNAs (tRNAs) and messenger RNA (mRNA) during translation by the ribosome. We report a crystal structure refined to 3.6 angstrom resolution of the ribosome trapped with EF-G in the posttranslocational state using the antibiotic fusidic acid. Fusidic acid traps EF-G in a conformation intermediate between the guanosine triphosphate and guanosine diphosphate forms. The interaction of EF-G with ribosomal elements implicated in stimulating catalysis, such as the L10-L12 stalk and the L11 region, and of domain IV of EF-G with the tRNA at the peptidyl-tRNA binding site (P site) and with mRNA shed light on the role of these elements in EF-G function in catalysis and translocation. The stabilization of the mobile stalks of the ribosome also results in a more complete description of its structure.
