EFFECTS OF INTERCISTRONIC LENGTH ON THE EFFICIENCY OF REINITIATION BY EUKARYOTIC RIBOSOMES
EFFECTS OF INTERCISTRONIC LENGTH ON THE EFFICIENCY OF REINITIATION BY EUKARYOTIC RIBOSOMES
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DOI：
10.1128/mcb.7.10.3438
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发表时间：
1987-10-01
影响因子：
5.3
通讯作者：
KOZAK, M
中科院分区：
文献类型：
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作者：
KOZAK, M
基于猿病毒 40 的质粒在 COS 细胞短期转染过程中指导前胰岛素原的合成，已被用于探测真核核糖体重新启动的机制。多个实验室的早期研究已经确定，在内部 AUG 密码子处重新启动翻译的能力取决于是否有一个终止密码子与前面的 AUG 三联体位于预期重新启动位点的上游。在目前的研究中，上游终止子密码子相对于前胰岛素原重启位点的位置已被系统地改变。随着顺反子间序列的延长，重新引发的效率逐渐提高。当上游“小顺反子”在前胰岛素原起始位点之前的 79 个核苷酸处终止时，胰岛素原的合成与没有上游 AUG 密码子一样有效。假设有一种机制可以解释这一结果，这有点令人惊讶，因为随着顺反子间间隙的扩大，细菌核糖体重新启动的效率较低。
Simian virus 40-based plasmids that direct the synthesis of preproinsulin during short-term transfection of COS cells have been used to probe the mechanism of reinitiation by eucaryotic ribosomes. Earlier studies from several laboratories had established that the ability to reinitiate translation at an internal AUG codon depends on having a terminator codon in frame with the preceding AUG triplet and upstream from the intended restart site. In the present studies, the position of the upstream terminator codon relative to the preproinsulin restart site has been systematically varied. The efficiency of reinitiation progressively improved as the intercistronic sequence was lengthened. When the upstream "minicistron" terminated 79 nucleotides before the preproinsulin start site, the synthesis of proinsulin was as efficient as if there were no upstream AUG codons. A mechanism is postulated that might account for this result, which is somewhat surprising inasmuch as bacterial ribosomes reinitate less efficiently as the intercistronic gap is widened.