Cell Biology

A Mitotic RNP

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Science  06 May 2005:
Vol. 308, Issue 5723, pp. 759
DOI: 10.1126/science.308.5723.759b

The mitotic spindle is an arrangement of cellular microtubules that acts as the physical scaffold used to partition chromosomes into the daughter cells during mitosis. Blower et al. find that an RNA-binding protein, Rae1, already known to be involved in the export of mRNA from the nucleus during interphase, also has a role in spindle assembly. Rae1 was isolated from Xenopus egg extracts as an activity required for spindle assembly. When it was depleted from egg extracts or from cells, mitotic spindle assembly was inhibited, and purified Rae1 stabilized microtubules in the presence of its nuclear import/export partners, the small GTPase Ran and importin β. Rae1 appears to be part of a large ribonucleoprotein (RNP) complex that controls microtubule dynamics; the association of RNA with the mitotic spindle is unanticipated but appears to be due to a structural requirement, perhaps as a second kind of scaffold. — SMH

Cell 121, 223 (2005).

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