Recent technological advances have expanded the annotated protein coding content of mammalian genomes, as hundreds of previously unidentified, short open reading frame (ORF)-encoded peptides (SEPs) have now been found to be translated. Although several studies have identified important physiological roles for this emerging protein class, a general method to define their interactomes is lacking. Here, we demonstrate that genetic incorporation of the photo-crosslinking noncanonical amino acid AbK into SEP transgenes allows for the facile identification of SEP cellular interaction partners using affinity-based methods. From a survey of seven SEPs, we report the discovery of short ORF-encoded histone binding protein (SEHBP), a conserved microprotein that interacts with chromatin-associated proteins, localizes to discrete genomic loci, and induces a robust transcriptional program when overexpressed in human cells. This work affords a straightforward method to help define the physiological roles of SEPs and demonstrates its utility by identifying SEHBP as a short ORF-encoded transcription factor.

最近的技术进步扩大了哺乳动物基因组的注释蛋白质编码内容，因为现在发现数百种先前未识别的短开放阅读框（ORF）编码肽（SEP）可以被翻译。尽管一些研究已经确定了这种新兴蛋白质类别的重要生理作用，但缺乏定义其相互作用组的通用方法。在这里，我们证明，将光交联非规范氨基酸 AbK 基因整合到 SEP 转基因中，可以使用基于亲和力的方法轻松识别 SEP 细胞相互作用伴侣。通过对七个 SEP 的调查，我们报告发现了短 ORF 编码的组蛋白结合蛋白 (SEHBP)，这是一种与染色质相关蛋白相互作用的保守微生物蛋白，定位于离散的基因组位点，当在人类细胞中过度表达时，会诱导强大的转录程序。这项工作提供了一种简单的方法来帮助定义 SEP 的生理作用，并通过将 SEHBP 识别为短 ORF 编码的转录因子来展示其实用性。