The nucleolus is essential for ribosome biogenesis and is involved in many other cellular functions. We performed a systematic spatiotemporal dissection of the human nucleolar proteome using confocal microscopy. In total, 1,318 nucleolar proteins were identified; 287 were localized to fibrillar components, and 157 were enriched along the nucleoplasmic border, indicating a potential fourth nucleolar subcompartment (nucleoli rim). We found 65 nucleolar proteins (36 uncharacterized) to relocate to the chromosomal periphery during mitosis. Interestingly, we observed temporal partitioning into two recruitment phenotypes: early (prometaphase) and late (after metaphase), suggesting phase-specific functions. We further show that expression of MKI67 is critical for this temporal partitioning. We provide the first proteome-wide analysis of intrinsic protein disorder for the human nucleolus and show that nucleolar proteins in general, and mitotic chromosome proteins in particular, have significantly higher intrinsic disorder level compared to cytosolic proteins. In summary, this study provides a comprehensive and essential resource of spatiotemporal expression data for the nucleolar proteome as part of the Human Protein Atlas.

中文翻译：

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核仁蛋白质组图谱揭示了与内在蛋白质失调有关的时空组织

核仁对于核糖体的生物发生至关重要，并参与许多其他细胞功能。我们使用共聚焦显微镜对人类核仁蛋白质组进行了系统的时空解剖。总共鉴定出1,318种核仁蛋白；287个位于原纤维成分，并且157个沿核质边界富集，表明潜在的第四个核仁小室（核仁边缘）。我们发现65个核仁蛋白（36个未表征）在有丝分裂过程中重新定位到染色体外围。有趣的是，我们观察到时间划分为两种募集表型：早期（前中期）和晚期（中期之后），提示阶段特异性功能。我们进一步表明，MKI67的表达对于这种时间分区至关重要。我们提供了针对人类核仁的内在蛋白质失调的首次蛋白质组范围分析，并显示与细胞溶质蛋白相比，一般而言，核仁蛋白，尤其是有丝分裂染色体蛋白具有明显更高的内在失调水平。总而言之，这项研究提供了作为人类蛋白质图谱一部分的核仁蛋白质组的时空表达数据的全面而必要的资源。