title: Tpr is localized within the nuclear basket of the pore complex and has a role in nuclear protein export.
abstract: Tpr is a coiled-coil protein found near the nucleoplasmic side of the pore complex. Since neither the precise localization of Tpr nor its functions are well defined, we generated antibodies to three regions of Tpr to clarify these issues. Using light and EM immunolocalization, we determined that mammalian Tpr is concentrated within the nuclear basket of the pore complex in a distribution similar to Nup153 and Nup98. Antibody localization together with imaging of GFP-Tpr in living cells revealed that Tpr is in discrete foci inside the nucleus similar to several other nucleoporins but is not present in intranuclear filamentous networks (Zimowska et al., 1997) or in long filaments extending from the pore complex (Cordes et al., 1997) as proposed. Injection of anti-Tpr antibodies into mitotic cells resulted in depletion of Tpr from the nuclear envelope without loss of other pore complex basket proteins. Whereas nuclear import mediated by a basic amino acid signal was unaffected, nuclear export mediated by a leucine-rich signal was retarded significantly. Nuclear injection of anti-Tpr antibodies in interphase cells similarly yielded inhibition of protein export but not import. These results indicate that Tpr is a nucleoporin of the nuclear basket with a role in nuclear protein export.
authors.affiliation: Department of Cell Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.
authors.forename: Phyllis
authors.initials: P
authors.lastname: Frosst
authors.forename: Tinglu
authors.initials: T
authors.lastname: Guan
authors.forename: Cecilia
authors.initials: C
authors.lastname: Subauste
authors.forename: Klaus
authors.initials: K
authors.lastname: Hahn
authors.forename: Larry
authors.initials: L
authors.lastname: Gerace
mesh_terms: D021581:Active Transport, Cell Nucleus; D000818:Animals; D000911:Antibodies, Monoclonal / Q000008:administration & dosage / Q000378:metabolism; D002020:Buffaloes; D002460:Cell Line; D049452:Green Fluorescent Proteins; D006367:HeLa Cells; D006801:Humans; D007150:Immunohistochemistry; D007399:Interphase; D008164:Luminescent Proteins / Q000378:metabolism; D008845:Microinjections / Q000379:methods; D008854:Microscopy, Electron / Q000379:methods; D008856:Microscopy, Fluorescence / Q000379:methods; D009685:Nuclear Envelope / Q000378:metabolism / Q000648:ultrastructure; D022022:Nuclear Pore / Q000378:metabolism / Q000648:ultrastructure; D028861:Nuclear Pore Complex Proteins / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000378:metabolism
chemical_list: D000911:Antibodies, Monoclonal; D008164:Luminescent Proteins; D028861:Nuclear Pore Complex Proteins; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D011993:Recombinant Fusion Proteins; C073597:TPR protein, human; D049452:Green Fluorescent Proteins