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Karyopherins in nuclear pore biogenesis

Karyopherins in nuclear pore biogenesis The mechanisms that govern the assembly of nuclear pore complexes (NPCs) remain largely unknown. Here, we have established a role for karyopherins in this process. We show that the yeast karyopherin Kap121p functions in the targeting and assembly of the nucleoporin Nup53p into NPCs by recognizing a nuclear localization signal (NLS) in Nup53p. This karyopherin-mediated function can also be performed by the Kap95p–Kap60p complex if the Kap121p-binding domain of Nup53p is replaced by a classical NLS, suggesting a more general role for karyopherins in NPC assembly. At the NPC, neighboring nucleoporins bind to two regions in Nup53p. One nucleoporin, Nup170p, associates with a region of Nup53p that overlaps with the Kap121p binding site and we show that they compete for binding to Nup53p. We propose that once targeted to the NPC, dissociation of the Kap121p–Nup53p complex is driven by the interaction of Nup53p with Nup170p. At the NPC, Nup53p exists in two separate complexes, one of which is capable of interacting with Kap121p and another that is bound to Nup170p. We propose that fluctuations between these two states drive the binding and release of Kap121p from Nup53p, thus facilitating Kap121p's movement through the NPC. nuclear envelope; nucleoporins; NPC assembly; nuclear transport Footnotes ↵ * Abbreviations used in this paper: FG, Phe-Gly; kap, karyopherin; KBD, Kap121p binding domain; NE, nuclear envelope; NES, nuclear export signal; NPC, nuclear pore complex; pA, protein A; ts, temperature sensitive. Submitted: 18 March 2002 Accepted: 10 September 2002 Revision received 6 September 2002 http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The Journal of Cell Biology Rockefeller University Press

Karyopherins in nuclear pore biogenesis

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Publisher
Rockefeller University Press
Copyright
Copyright © 2002, by The Rockefeller University Press
ISSN
0021-9525
eISSN
1540-8140
DOI
10.1083/jcb.200203079
pmid
12403813
Publisher site
See Article on Publisher Site

Abstract

The mechanisms that govern the assembly of nuclear pore complexes (NPCs) remain largely unknown. Here, we have established a role for karyopherins in this process. We show that the yeast karyopherin Kap121p functions in the targeting and assembly of the nucleoporin Nup53p into NPCs by recognizing a nuclear localization signal (NLS) in Nup53p. This karyopherin-mediated function can also be performed by the Kap95p–Kap60p complex if the Kap121p-binding domain of Nup53p is replaced by a classical NLS, suggesting a more general role for karyopherins in NPC assembly. At the NPC, neighboring nucleoporins bind to two regions in Nup53p. One nucleoporin, Nup170p, associates with a region of Nup53p that overlaps with the Kap121p binding site and we show that they compete for binding to Nup53p. We propose that once targeted to the NPC, dissociation of the Kap121p–Nup53p complex is driven by the interaction of Nup53p with Nup170p. At the NPC, Nup53p exists in two separate complexes, one of which is capable of interacting with Kap121p and another that is bound to Nup170p. We propose that fluctuations between these two states drive the binding and release of Kap121p from Nup53p, thus facilitating Kap121p's movement through the NPC. nuclear envelope; nucleoporins; NPC assembly; nuclear transport Footnotes ↵ * Abbreviations used in this paper: FG, Phe-Gly; kap, karyopherin; KBD, Kap121p binding domain; NE, nuclear envelope; NES, nuclear export signal; NPC, nuclear pore complex; pA, protein A; ts, temperature sensitive. Submitted: 18 March 2002 Accepted: 10 September 2002 Revision received 6 September 2002

Journal

The Journal of Cell Biology – Rockefeller University Press

Published: Oct 28, 2002

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