In addition to the main, protein-coding, open reading frame (mORF), many eukaryotic mRNAs contain upstream ORFs (uORFs) initiated at AUG or near-cognate codons residing 5′ of the mORF start site. Whereas translation of uORFs generally represses translation of the mORFs, a subset of uORFs serves as a nexus for regulating translation of the mORF. In this review, we summarize the mechanisms by which uORFs can repress or stimulate mRNA translation, highlight uORF-mediated translational repression involving ribosome queuing, and critically evaluate recently described alternatives to the delayed reinitiation model for uORF-mediated regulation of the GCN4/ATF4 mRNAs.

中文翻译：

---

uORF 的翻译调控和起始密码子选择严格性

除了主要的蛋白质编码开放阅读框 (mORF) 之外，许多真核 mRNA 还包含起始于 AUG 的上游 ORF (uORF) 或位于 mORF 起始位点 5' 的近同源密码子。虽然uORF的翻译通常抑制mORF的翻译，但uORF的子集充当调节mORF翻译的纽带。在这篇综述中，我们总结了 uORF 抑制或刺激 mRNA 翻译的机制，强调了 uORF 介导的涉及核糖体排队的翻译抑制，并批判性地评估了最近描述的 uORF 介导的 GCN4 / ATF4 mRNA 调节延迟重新启动模型的替代方案。