核糖体分析实验支持一系列新颖的人类开放阅读框架的翻译。相比之下，来自大规模蛋白质组学实验的大多数肽仅源自一个来源，即 5' 非翻译区。在整个人类基因组中，我们发现了 192 个翻译上游区域的证据，其中大部分会产生具有延伸 N 末端的蛋白质亚型。几乎所有这些 N 末端延伸都来自高度丰富的基因，这表明我们检测到的新区域只是冰山一角。这些上游区域具有编码外显子不典型的特征。它们的 GC 含量非常高，甚至高于其他基因的 5' 区域，并且大多数具有非规范起始密码子。尽管一些新的上游区域具有跨物种保守性（例如，无脊椎动物中有五个具有直系同源物），但三分之二的阅读框在猿类之外并不保守。这些非保守区域也没有纯化选择的证据，这表明这种翻译大部分不起作用。此外，癌细胞系中非保守上游区域的肽明显多于预期，这强烈表明异常或嘈杂的翻译起始过程可能在上游区域的翻译中发挥重要作用。© 作者 2024 . 由牛津大学出版社代表核酸研究出版。

Ribosome profiling experiments support the translation of a range of novel human open reading frames. By contrast, most peptides from large-scale proteomics experiments derive from just one source, 5' untranslated regions. Across the human genome we find evidence for 192 translated upstream regions, most of which would produce protein isoforms with extended N-terminal ends. Almost all of these N-terminal extensions are from highly abundant genes, which suggests that the novel regions we detect are just the tip of the iceberg. These upstream regions have characteristics that are not typical of coding exons. Their GC-content is remarkably high, even higher than 5' regions in other genes, and a large majority have non-canonical start codons. Although some novel upstream regions have cross-species conservation - five have orthologues in invertebrates for example - the reading frames of two thirds are not conserved beyond simians. These non-conserved regions also have no evidence of purifying selection, which suggests that much of this translation is not functional. In addition, non-conserved upstream regions have significantly more peptides in cancer cell lines than would be expected, a strong indication that an aberrant or noisy translation initiation process may play an important role in translation from upstream regions.© The Author(s) 2024. Published by Oxford University Press on behalf of Nucleic Acids Research.