Kristensen Ole, Laurberg Martin, Liljas Anders, Selmer Maria
Molecular Biophysics, Centre for Chemistry and Chemical Engineering, Lund University, Box 124, SE-221 00 Lund, Sweden.
Curr Protein Pept Sci. 2002 Feb;3(1):133-41. doi: 10.2174/1389203023380837.
tRNA is the adaptor in the translation process. The ribosome has three sites for tRNA, the A-, P-, and E-sites. The tRNAs bridge between the ribosomal subunits with the decoding site and the mRNA on the small or 30S subunit and the peptidyl transfer site on the large or 50S subunit. The possibility that translation release factors could mimic tRNA has been discussed for a long time, since their function is very similar to that of tRNA. They identify stop codons of the mRNA presented in the decoding site and hydrolyse the nascent peptide from the peptidyl tRNA in the peptidyl transfer site. The structures of eubacterial release factors are not yet known, and the first example of tRNA mimicry was discovered when elongation factor G (EF-G) was found to have a closely similar shape to a complex of elongation factor Tu (EF-Tu) with aminoacyl-tRNA. An even closer imitation of the tRNA shape is seen in ribosome recycling factor (RRF). The number of proteins mimicking tRNA is rapidly increasing. This primarily concerns translation factors. It is now evident that in some sense they are either tRNA mimics, GTPases or possibly both.
转运RNA（tRNA）是翻译过程中的衔接分子。核糖体有三个tRNA结合位点，即A位点、P位点和E位点。tRNA在核糖体亚基之间起桥梁作用，其解码位点与小亚基（30S）上的信使核糖核酸（mRNA）以及大亚基（50S）上的肽基转移位点相连。由于翻译释放因子的功能与tRNA非常相似，因此人们对其是否能模拟tRNA进行了长期讨论。它们识别解码位点上呈现的mRNA的终止密码子，并在肽基转移位点将新生肽从肽基tRNA上水解下来。真细菌释放因子的结构尚不清楚，当发现延伸因子G（EF-G）与氨酰tRNA的延伸因子Tu（EF-Tu）复合物形状极为相似时，首次发现了tRNA模拟现象。核糖体循环因子（RRF）对tRNA形状的模仿更为逼真。模拟tRNA的蛋白质数量正在迅速增加。这主要涉及翻译因子。现在很明显，从某种意义上说，它们要么是tRNA模拟物，要么是GTP酶，或者可能两者皆是。
