Altmann M, Wittmer B, Méthot N, Sonenberg N, Trachsel H
Institute of Biochemistry and Molecular Biology, University of Berne, Switzerland.
EMBO J. 1995 Aug 1;14(15):3820-7. doi: 10.1002/j.1460-2075.1995.tb00051.x.
The Saccharomyces cerevisiae TIF3 gene encodes the yeast homologue of mammalian translation initiation factor eIF-4B. We have added six histidine residues to the C-terminus of Tif3 protein (Tif3-His6p) and purified the tagged protein by affinity chromatography. Tif3-His6p stimulates translation and mRNA binding to ribosomes in a Tif3-dependent in vitro system. Furthermore, it binds to single-stranded RNA and catalyses the annealing of partially complementary RNA strands in vitro. In parallel experiments, RNA annealing activity could also be demonstrated for mammalian eIF-4B. A role for Tif3/eIF-4B and RNA annealing activity in the scanning process is proposed.
酿酒酵母TIF3基因编码哺乳动物翻译起始因子eIF-4B的酵母同源物。我们在Tif3蛋白（Tif3-His6p）的C末端添加了六个组氨酸残基，并通过亲和层析纯化了带标签的蛋白。Tif3-His6p在依赖Tif3的体外系统中刺激翻译以及mRNA与核糖体的结合。此外，它能结合单链RNA并在体外催化部分互补RNA链的退火。在平行实验中，也能证明哺乳动物eIF-4B具有RNA退火活性。我们提出了Tif3/eIF-4B和RNA退火活性在扫描过程中的作用。
