Nuclear import of the TATA-binding protein: mediation by the karyopherin Kap114p and a possible mechanism for intranuclear targeting

J Cell Biol. 1999 Jun 28;145(7):1407-17. doi: 10.1083/jcb.145.7.1407.

Abstract

Binding of the TATA-binding protein (TBP) to the promoter is the first and rate limiting step in the formation of transcriptional complexes. We show here that nuclear import of TBP is mediated by a new karyopherin (Kap) (importin) family member, Kap114p. Kap114p is localized to the cytoplasm and nucleus. A complex of Kap114p and TBP was detected in the cytosol and could be reconstituted using recombinant proteins, suggesting that the interaction was direct. Deletion of the KAP114 gene led to specific mislocalization of TBP to the cytoplasm. We also describe two other potential minor import pathways for TBP. Consistent with other Kaps, the dissociation of TBP from Kap114p is dependent on RanGTP. However, we could show that double stranded, TATA-containing DNA stimulates this RanGTP-mediated dissociation of TBP, and is necessary at lower RanGTP concentrations. This suggests a mechanism where, once in the nucleus, TBP is preferentially released from Kap114p at the promoter of genes to be transcribed. In this fashion Kap114p may play a role in the intranuclear targeting of TBP.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Biological Transport
  • Carrier Proteins / analysis
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism*
  • Cell Nucleus / chemistry
  • Cell Nucleus / metabolism*
  • Cytoplasm / chemistry
  • Cytoplasm / metabolism
  • DNA / genetics
  • DNA / pharmacology
  • DNA-Binding Proteins / analysis
  • DNA-Binding Proteins / metabolism*
  • Fungal Proteins / analysis
  • Fungal Proteins / genetics
  • Fungal Proteins / metabolism*
  • Gene Deletion
  • Genes, Essential
  • Genes, Fungal / genetics
  • Guanosine Triphosphate / metabolism
  • Guanosine Triphosphate / pharmacology
  • Karyopherins
  • Nuclear Localization Signals*
  • Nuclear Proteins / analysis
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism*
  • Nuclear Proteins / pharmacology
  • Protein Binding / drug effects
  • Recombinant Fusion Proteins / analysis
  • Recombinant Fusion Proteins / metabolism
  • Saccharomyces cerevisiae / cytology
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / growth & development
  • Saccharomyces cerevisiae / metabolism*
  • TATA Box / genetics
  • TATA-Box Binding Protein
  • Transcription Factor TFIIA
  • Transcription Factors / analysis
  • Transcription Factors / metabolism*
  • Transcription Factors / pharmacology
  • ran GTP-Binding Protein

Substances

  • Carrier Proteins
  • DNA-Binding Proteins
  • Fungal Proteins
  • Karyopherins
  • Nuclear Localization Signals
  • Nuclear Proteins
  • Recombinant Fusion Proteins
  • TATA-Box Binding Protein
  • Transcription Factor TFIIA
  • Transcription Factors
  • Guanosine Triphosphate
  • DNA
  • ran GTP-Binding Protein