Cell Biology

Stable, yet Dynamic

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Science  27 Jul 2001:
Vol. 293, Issue 5530, pp. 577
DOI: 10.1126/science.293.5530.577a

The nucleus of eukaryotic cells is surrounded by a double membrane, the nuclear envelope (NE), which contains nuclear pore complexes (NPCs) that allow nucleocytoplasmic movement of proteins and RNAs during interphase. The nuclear envelope breaks down during mitosis, releasing the nuclear contents and enabling segregation of replicated chromosomes into the two daughter cells.

Daigle et al. examined the characteristics of NPCs in situ using fluorescently tagged nuclear pore proteins. In interphase, the pores were remarkably still; no disorderly pore movement was observed although large arrays of NPCs moved en bloc as the nucleus changed shape. In addition, fluorescence recovery after photobleaching (FRAP) measurements revealed that almost no turnover of NPC components occurred. However, during mitosis, NPCs completely disassembled and were then recruited to chromatin near the end of mitosis at anaphase. This malleable network of nuclear pores is likely to be important in maintaining intranuclear structure and function. — SMH

J. Cell Biol.154, 71 (2001).

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