Abstract

The abundance of noncanonical mechanisms of eukaryotic initiation of translation indicates their involvement in the regulation of protein synthesis during key events in a cell life. One of the well-known examples of a noncanonical cap-independent process is the initiation of translation of mRNA with the 5'‑untranslated (leader) region of the messenger encoding for the photoprotein obelin (the obelin leader). In the present work, mRNA with the obelin leader was modified by adding 45 deoxycytidyl nucleotides and a fluorescent label to its 5 'end. Formation of the 48S ribosomal initiation complexes at the start codon of the modified mRNA was studied using primer extension inhibition (toeprinting). In contrast to mRNA with the intact obelin leader, translation initiation of which strictly requires the eIF4F factor, initiation on the modified mRNA can take place in the absence of this factor, although with less efficiency. The finding thus indicates the unknown function of the eIF4F factor in the first step(s) of mRNA recognition by ribosomal subunits.

中文翻译：

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的mRNA前导序列的5'末端的修改会更改启动翻译所必需的启动因子集。

摘要

真核生物翻译非典机制的丰富性表明它们参与细胞生命关键事件中蛋白质合成的调控。非经典的不依赖帽的过程的一个众所周知的例子是，mRNA的翻译带有编码光蛋白obelin（obelin前导）的信使的5'-非翻译（前导）区域。在目前的工作中，通过在其5'末端添加45个脱氧胞苷基核苷酸和一个荧光标记来修饰带有obelin前导序列的mRNA。使用引物延伸抑制（toeprinting）研究了在修饰的mRNA的起始密码子处48S核糖体起始复合物的形成。与具有完整的obelin前导序列的mRNA不同，后者的翻译起始严格要求eIF4F因子，尽管效率较低，但在缺少该因子的情况下可以在修饰的mRNA上进行启动。因此，该发现表明在核糖体亚基识别mRNA的第一步中，eIF4F因子的功能未知。