Cell Biology

Nuclear Organization

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Science  21 Jan 2000:
Vol. 287, Issue 5452, pp. 393
DOI: 10.1126/science.287.5452.393b

The transport of small molecules by passive diffusion and of proteins and RNAs by active transport into and out of the eukaryotic nucleus takes place through nuclear pore complexes (NPC). The yeast proteins Mlp1p and Mlp2p were identified in a screen for NPC-associated proteins and have been localized to filamentous structures that extend from the nuclear pore ring into the nucleoplasm. Galy et al. find that deletion of Mlp2 reduces DNA repair efficiency, similar to what is seen upon deletion of Yku70p, a protein that is known to bind to the ends of chromosomes—the telomeres—and has been localized to the periphery of the nucleoplasm. The perinuclear localization of telomeres and their associated proteins also appears to contribute to the repressive effect of telomeres on the transcription of nearby genes. Further analysis showed that deletion of Mlp2 disperses Yku70p throughout the nucleoplasm and that proper localization is mediated by a direct association of the two proteins. Another intriguing connection between the NPC and telomeres comes from the observation that truncating the nucleoporin Nup145p produces aberrant localization of the Mlp proteins and of Rap1p, another telomere-binding protein, and also a de-repression of a subtelomeric gene. How all of these results fit together is not yet clear, but the linkage between telomeric localization and function and the NPC warrants a closer look.—BAP

Nature403, 108 (2000)

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