Identification of the full complement of genes in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a crucial step towards gaining a fuller understanding of its molecular biology. However, short and/or overlapping genes can be difficult to detect using conventional computational approaches, whereas high-throughput experimental approaches – such as ribosome profiling – cannot distinguish translation of functional peptides from regulatory translation or translational noise. By studying regions showing enhanced conservation at synonymous sites in alignments of SARS-CoV-2 and related viruses (subgenus Sarbecovirus) and correlating the results with the conserved presence of an open reading frame (ORF) and a plausible translation mechanism, a putative new gene – ORF3c – was identified. ORF3c overlaps ORF3a in an alternative reading frame. A recently published ribosome profiling study confirmed that ORF3c is indeed translated during infection. ORF3c is conserved across the subgenus Sarbecovirus, and encodes a 40–41 amino acid predicted transmembrane protein.

中文翻译：

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一种推定的新 SARS-CoV 蛋白 3c，在与 ORF3a 重叠的 ORF 中编码。

鉴定严重急性呼吸综合征冠状病毒 2 (SARS-CoV-2) 的全部基因是更全面了解其分子生物学的关键一步。然而，使用传统的计算方法可能难以检测短和/或重叠的基因，而高通量实验方法（例如核糖体分析）无法区分功能肽的翻译与调节翻译或翻译噪声。通过研究 SARS-CoV-2 和相关病毒（ Sarbecovirus亚属）同义位点的保守性增强的区域，并将结果与​​开放阅读框 (ORF) 的保守存在和合理的翻译机制相关联，一个假定的新基因– ORF3c – 已被识别。ORF3c 在替代阅读框中与 ORF3a 重叠。最近发表的一项核糖体分析研究证实，ORF3c 确实在感染过程中被翻译。ORF3c 在Sarbecovirus亚属中是保守的，编码 40-41 个氨基酸的预测跨膜蛋白。