Cloning and characterization of human karyopherin β3

Nabeel R. Yaseen, Günter Blobel

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115 Scopus citations


Nuclear import of classical nuclear localization sequence-bearing proteins is mediated by karyopherin α/β1 heterodimers. A second nuclear import pathway, mediated by karyopherin β2 (transportin), recently was described for mRNA-binding proteins. Here we report the cloning and characterization of human karyopherin β3, which may be involved in a third pathway for nuclear import. Karyopherin β3 was localized mainly to the cytosol and the nucleus, particularly the nuclear rim. It bound to several of the repeat-containing nucleoporins (Nup358, Nup214, Nup153, Nup98, and p62) in overlay and solution-binding assays and was competed away by karyopherin β1. For Nup98, we localized this binding to the peptide repeat-containing region. Karyopherin β3 contains two putative Ran-binding homology regions and bound to RAN-GTP in a solution-binding assay with much higher affinity than to Ran-GDP. Furthermore, it interacted with two ribosomal proteins in an overlay assay. We suggest that karyopherin β3 is a nuclear transport factor that may mediate the import of some ribosomal proteins into the nucleus.

Original languageEnglish (US)
Pages (from-to)4451-4456
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number9
StatePublished - Apr 29 1997

ASJC Scopus subject areas

  • General


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