Sherman F, Stewart J W, Schweingruber A M
Cell. 1980 May;20(1):215-22. doi: 10.1016/0092-8674(80)90249-4.
We used a specially constructed strain, cyc1-345, of the yeast Saccharomyces cerevisiae to isolate revertants that initiated translation of iso-1-cytochrome c at various sites along an extended region of the mRNA. Normal amounts of iso-1-cytochrome c occurred when translation initiated at the abnormal sites corresponding to amino acid positions -3, -2, 3 and 5, as well as the normal position -1; 20% of the normal amounts occurred when translation initiated at the abnormal position 9. These results with cyc1-345 revertants indicate that translation of iso-1-cytochrome c can initiate with the normal efficiency at any site within the region spanning 25 nucleotides. Furthermore, because the lower amount of the short iso-1-cytochrome c in the mutant initiating at position 9 may not necessarily reflect an inefficiency of translation, we believe that translation can initiate with normal or near-normal efficiencies at any site within a 37 nucleotide region, and presumably at any site preceding and following that of the normal initiation codon. These results establish that there is no absolute requirement for a particular sequence 5' to the initiation codon, and are consistent with our previous suggestion that translation starts at the AUG codon closest to the 5' end of the mRNA.
我们使用了酿酒酵母的一种特殊构建菌株cyc1 - 345来分离回复突变体，这些回复突变体可在mRNA的一个延伸区域内的不同位点起始iso - 1 - 细胞色素c的翻译。当翻译在对应于氨基酸位置 - 3、 - 2、3和5以及正常位置 - 1的异常位点起始时，会出现正常量的iso - 1 - 细胞色素c；当翻译在异常位置9起始时，出现的量为正常量的20%。cyc1 - 345回复突变体的这些结果表明，iso - 1 - 细胞色素c的翻译可以在跨越25个核苷酸的区域内的任何位点以正常效率起始。此外，由于在位置9起始的突变体中短iso - 1 - 细胞色素c的量较低不一定反映翻译效率低下，我们认为翻译可以在37个核苷酸区域内的任何位点以正常或接近正常的效率起始，并且大概在正常起始密码子之前和之后的任何位点都可以。这些结果表明，起始密码子5'端不存在对特定序列的绝对要求，并且与我们之前提出的翻译从最接近mRNA 5'端的AUG密码子开始的建议一致。
