The nucleolus is a distinct subnuclear compartment that was first observed more than 200
years ago. Nucleoli assemble around the tandemly repeated ribosomal DNA gene clusters …

Speckles are subnuclear structures that are enriched in pre-messenger RNA splicing factors
and are located in the interchromatin regions of the nucleoplasm of mammalian cells. At the …

… We thank Dimitris Xirodimas for critical reading of the manuscript and members of the Lamond
laboratory for helpful discussions and advice. This work was funded by a Wellcome Trust …

Measuring the properties of endogenous cell proteins, such as expression level, subcellular
localization, and turnover rates, on a whole proteome level remains a major challenge in the …

… Fox for providing the HeLa YFP–p68 cell line and other members of the Lamond and the
Mann laboratories for help and discussions. Work in the Center for Experimental Bioinformatics (…

… Panel (Ai) shows an intact HeLa cell stained with two nucleolar-specific labels: Pyronin Y
(red) and nucleolin antibody (green). These reagents were also used to stain purified nucleoli (…

In a previous proteomic study of the human spliceosome, we identified 42 spliceosome-associated
factors, including 19 novel ones. Using enhanced mass spectrometric tools and …

Current evidence suggests that the nucleus has a distinct substructure, albeit one that is
dynamic rather than a rigid framework. Viral infection, oncogene expression, and inherited …

… We thank members of the Spector and Lamond groups for helpful comments. Angus Lamond
is a Wellcome Trust Principal Research Fellow. David L. Spector is funded by NIGMS/NIH …

… makes it an ideal candidate for biochemical 4 Correspondence: ailamond@dundee.ac.uk …
The extent of the nucleus is shown with DAPI staining in panels (Ai)–(Bi), the fluorescence …