title: Paired-type homeodomain transcription factors are imported into the nucleus by karyopherin 13.
abstract: We report that the paired homeodomain transcription factor Pax6 is imported into the nucleus by the Karyopherin beta family member Karyopherin 13 (Kap13). Pax6 was identified as a potential cargo for Kap13 by a yeast two-hybrid screen. Direct binding of Pax6 to Kap13 was subsequently confirmed by in vitro assays with recombinant proteins, and binding in vivo was shown by coimmunoprecipitation. Ran-dependent import of Pax6 by Kap13 was shown to occur by using a digitonin-permeabilized cells assay. Kap13 binds to Pax6 via a nuclear localization sequence (NLS), which is located within a segment of 80 amino acid residues that includes the homeodomain. Kap13 showed reduced binding to Pax6 when either region located at each end of the homeodomain (208 to 214 and 261 to 267) was deleted. The paired-type homeodomain transcription factor family includes more than 20 members. All members contain a region similar to the NLS found in Pax6 and are therefore likely to be imported by Kap13. We confirmed this hypothesis for Pax3 and Crx, which bind to and are imported by Kap13.
authors.affiliation: The Carl C. Icahn Center for Gene Therapy and Molecular Medicine, Box 1496, The Mount Sinai School of Medicine, One Gustave L. Levy Place, New York, NY 10029, USA. Jonathan.Ploski@mssm.edu
authors.forename: Jonathan E
authors.initials: JE
authors.lastname: Ploski
authors.forename: Monee K
authors.initials: MK
authors.lastname: Shamsher
authors.forename: Aurelian
authors.initials: A
authors.lastname: Radu
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism*; D005136:Eye Proteins; D006367:HeLa Cells; D018398:Homeodomain Proteins / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D000071841:PAX6 Transcription Factor; D051761:Paired Box Transcription Factors; D017434:Protein Structure, Tertiary; D021381:Protein Transport / Q000502:physiology; D012097:Repressor Proteins; D016415:Sequence Alignment; D014157:Transcription Factors / Q000378:metabolism*; D020798:Two-Hybrid System Techniques; D028961:beta Karyopherins / Q000378:metabolism*
chemical_list: D000596:Amino Acids; D005136:Eye Proteins; D018398:Homeodomain Proteins; D000071841:PAX6 Transcription Factor; C000605730:PAX6 protein, human; D051761:Paired Box Transcription Factors; D012097:Repressor Proteins; D014157:Transcription Factors; D028961:beta Karyopherins