PerspectiveCELL CYCLE

Some Importin News About Spindle Assembly

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Science  02 Mar 2001:
Vol. 291, Issue 5509, pp. 1718-1719
DOI: 10.1126/science.1059765

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Summary

The cellular events that direct the polymerization of microtubules and assembly of the spindle apparatus during cell division are slowly being unraveled. In a Perspective, Kahana and Cleveland discuss new findings showing that the importins, which are nuclear transport proteins, block the stabilization and organization of microtubules by binding to NuMA and TPX2, nuclear proteins that are required for organizing the spindle poles. The small guanosine triphosphatase Ran regulates this binding by associating with the importins, inducing them to release NuMA and TPX2.