BACKGROUND The origin of the selective nuclear protein import machinery, which consists of nuclear pore complexes and adaptor molecules interacting with the nuclear localization signals (NLSs) of cargo molecules, is one of the most important events in the evolution of eukaryotic cells. How proteins were selected for import into the forming nucleus remains an open question. RESULTS Here, we demonstrate that functional NLSs may be integrated in the nucleotide-binding domains of both eukaryotic and prokaryotic proteins and may coevolve with these domains. CONCLUSION The presence of sequences similar to NLSs in the DNA-binding domains of prokaryotic proteins might have created an advantage for nuclear accumulation of these proteins during evolution of the nuclear-cytoplasmic barrier, influencing which proteins accumulated and became compartmentalized inside the forming nucleus (i.e., the content of the nuclear proteome). REVIEWERS This article was reviewed by Sergey Melnikov and Igor Rogozin. OPEN PEER REVIEW Reviewed by Sergey Melnikov and Igor Rogozin. For the full reviews, please go to the Reviewers' comments section.

中文翻译：

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基于原核蛋白中预先存在的核定位信号的核蛋白质组的起源。

背景技术由核孔复合体和衔接物分子与货物分子的核定位信号（NLSs）相互作用的选择性核蛋白输入机制的起源是真核细胞进化中最重要的事件之一。如何选择蛋白质导入形成核仍是一个悬而未决的问题。结果在这里，我们证明功能性NLS可能整合在真核和原核蛋白的核苷酸结合结构域中，并且可能与这些结构域共同进化。结论在原核蛋白质的DNA结合结构域中存在与NLS相似的序列可能为核蛋白质屏障进化过程中这些蛋白质的核积累创造了优势，影响哪些蛋白质积累并在形成核内被分隔（即，核蛋白质组的含量）。审阅者本文由Sergey Melnikov和Igor Rogozin审阅。公开同行审查由Sergey Melnikov和Igor Rogozin进行审查。有关完整的评论，请转到“评论者的评论”部分。