In addition to canonical open reading frames (ORFs), thousands of translated small ORFs (containing less than 100 codons) have been identified in untranslated mRNA regions (UTRs) across eukaryotes. Small ORFs in 5′ UTRs (upstream (u)ORFs) often repress translation of the canonical ORF within the same mRNA. However, the function of translated small ORFs in the 3′ UTRs (downstream (d)ORFs) is unknown. Contrary to uORFs, we find that translation of dORFs enhances translation of their corresponding canonical ORFs. This translation stimulatory effect of dORFs depends on the number of dORFs, but not the length or peptide they encode. We propose that dORFs represent a new, strong, and universal translation regulatory mechanism in vertebrates.

中文翻译：

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较小的下游ORF的翻译可增强标准主开放阅读框的翻译。

除了规范的开放阅读框（ORF），在真核生物的非翻译mRNA区域（UTR）中还鉴定了成千上万个翻译的小ORF（包含少于100个密码子）。5'UTR（上游（u）ORF）中的小ORF通常会抑制同一mRNA中经典ORF的翻译。但是，在3'UTR（下游（d）ORF）中翻译的小ORF的功能尚不清楚。与uORF相反，我们发现dORF的翻译增强了其对应的规范ORF的翻译。dORF的这种翻译刺激作用取决于dORF的数量，而不取决于它们编码的长度或肽。我们建议dORFs代表脊椎动物中的新的，强大的和普遍的翻译监管机制。