Cell Biology

A Nuclear Bouncer

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Science  13 Aug 2004:
Vol. 305, Issue 5686, pp. 919
DOI: 10.1126/science.305.5686.919d

In eukaryotic cells, the nucleus contains a defined set of proteins, which are, of course, manufactured in the cytosol. This compartmentalization is enforced by the double membrane of the nuclear envelope, which is punctuated by nuclear pore complexes. Extensive trafficking of proteins and RNAs between the cytoplasm and the nucleus via the nuclear pores is essential for regulating gene expression. Mingot et al. now characterize the role of the protein RanBP16/exportin 7, which mediates the nuclear export of a variety of protein substrates, such as p50RhoGap and 14-3-3s. Exportin 7 binds to folded motifs that contain basic residues, unlike the short leucine-rich linear stretches of amino acids that are recognized by one of the other well-known nuclear exporters, CRM1. Exportin 7 escorts multiple cytosolic proteins from the nucleus back into the cytoplasm, and thus may function to exclude numerous proteins that otherwise would interfere with gene expression if allowed to gather in the nucleus. — SMH

EMBO J. 10.1038/sj.emboj.7600338 (2004).

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