Eukaryotic translation initiation relies on the m⁷G cap present at the 5′ end of all mRNAs. Some viral mRNAs employ alternative mechanisms of initiation based on internal ribosome entry. The ‘IRES ideology’ was adopted by researchers to explain the differential translation of cellular mRNAs when the cap recognition is suppressed. However, some cellular IRESs have already been challenged and others are awaiting their validation. As an alternative cap-independent mechanism, we propose adopting the concept of cap-independent translation enhancers (CITEs) for mammalian mRNAs. Unlike IRESs, CITEs can be located both within 5′ and 3′ UTRs and bind mRNA-recruiting translational components. The respective 5′ UTRs are then inspected by the scanning machinery essentially in the same way as under cap-dependent translation.

真核翻译起始依赖于m ⁷G cap存在于所有mRNA的5'端。一些病毒mRNA采用基于内部核糖体进入的其他启动机制。研究人员采用“ IRES意识形态”来解释当帽识别被抑制时细胞mRNA的差异翻译。但是，一些蜂窝IRES已经受到挑战，其他一些正在等待其验证。作为一种可选的不依赖于帽的机制，我们建议采用哺乳动物mRNA的不依赖帽的翻译增强子（CITE）的概念。与IRES不同，CITE可以位于5'和3'UTR内，并结合招募mRNA的翻译成分。然后，基本上以与取决于盖的平移相同的方式，通过扫描机器检查相应的5'UTR。