Cell Biology

B Comes Before A

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Science  05 Jan 2001:
Vol. 291, Issue 5501, pp. 15-17
DOI: 10.1126/science.291.5501.15e

During mitosis, mammalian cells break down their nucleus in order to separate and allocate the replicated chromosomes. After mitosis, cells must rebuild the nucleus, which includes the construction of the nuclear envelope, a double membrane penetrated by nuclear pores through which macromolecules are transported. One kit of components of intact nuclear envelopes is a set of scaffolding proteins known as the lamins, which line the inside of the nuclear envelope.

Moir et al. used green fluorescent protein-tagged lamins to visualize nuclear lamin re-assembly. They observed that lamin B1 binds to the condensed chromosomes as soon as the cell starts to exit mitosis. As lipids are recruited to form the nuclear envelope, lamin B1 spreads out to line the newly formed nucleoplasmic surface of the membrane. Relatively late in the process lamin A is co-opted into the nuclear lamina, probably serving to strengthen the final underpinning of the envelope. — SMH

J. Cell Biol.151, 1155 (2000).

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