Nuclear import of TFIIB is mediated by Kap114p, a karyopherin with multiple cargo-binding domains

Jennifer L. Hodges, Jennifer H. Leslie, Nima Mosammaparast, Yurong Guo, Jeffrey Shabanowitz, Donald F. Hunt, Lucy F. Pemberton

Research output: Contribution to journalArticlepeer-review

13 Scopus citations

Abstract

Nuclear import and export is mediated by an evolutionary conserved family of soluble transport factors, the karyopherins (referred to as importins and exportins). The yeast karyopherin Kap114p has previously been shown to import histones H2A and H2B, Nap1p, and a component of the preinitiation complex (PIC), TBP. Using a proteomic approach, we have identified several potentially new cargoes for Kap114p. These cargoes include another PIC component, the general transcription factor IIB or Sua7p, which interacted directly with Kap114p. Consistent with its role as a Sua7p import factor, deletion of KAP114 led to specific mislocalization of Sua7p to the cytoplasm. An interaction between Sua7p and TBP was also detected in cytosol, raising the possibility that both Sua7p and TBP can be coimported by Kap114p. We have also shown that Kapll4p possesses multiple overlapping binding sites for its partners, Sua7p, Nap1p, and H2A and H2B, as well as RanGTP and nucleoporins. In addition, we have assembled an in vitro complex containing Sua7p, Nap1p, and histones H2A and H2B, suggesting that this Kap may import several proteins simultaneously. The import of more than one cargo at a time would increase the efficiency of each import cycle and may allow the regulation of coimported cargoes.

Original languageEnglish
Pages (from-to)3200-3210
Number of pages11
JournalMolecular biology of the cell
Volume16
Issue number7
DOIs
StatePublished - Jul 2005

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