Karyopherins in nuclear pore biogenesis: a role for Kap121p in the assembly of Nup53p into nuclear pore complexes

TitleKaryopherins in nuclear pore biogenesis: a role for Kap121p in the assembly of Nup53p into nuclear pore complexes
Publication TypeJournal Article
Year of Publication2002
AuthorsLusk CP, Makhnevych T, Marelli M, Aitchison JD, Wozniak RW
JournalJ Cell Biol
Date PublishedOct 28
Keywords*Membrane Transport Proteins, Binding Sites/physiology, Karyopherins/*metabolism, Mutagenesis/physiology, Nuclear Pore Complex Proteins/chemistry/genetics/*metabolism, Nuclear Pore/*metabolism, Protein Structure, Tertiary, Receptors, Cytoplasmic and Nuclear/chemistry/*metabolism, Saccharomyces cerevisiae Proteins/chemistry/genetics/*metabolism, Yeasts/metabolism
AbstractThe 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.
Short TitleThe Journal of cell biology
Alternate JournalThe Journal of cell biology