title: Nup98 localizes to both nuclear and cytoplasmic sides of the nuclear pore and binds to two distinct nucleoporin subcomplexes.
abstract: The vertebrate nuclear pore is an enormous structure that spans the double membrane of the nuclear envelope. In yeast, most nucleoporins are found symmetrically on both the nuclear and cytoplasmic sides of the structure. However, in vertebrates most nucleoporins have been localized exclusively to one side of the nuclear pore. Herein, we show, by immunofluorescence and immunoelectron microscopy, that Nup98 is found on both sides of the pore complex. Additionally, we find that the pore-targeting domain of Nup98 interacts directly with the cytoplasmic nucleoporin Nup88, a component of the Nup214, Nup88, Nup62 subcomplex. Nup98 was previously described to interact with the nuclear-oriented Nup160, 133, 107, 96 complex through direct binding to Nup96. Interestingly, the same site within Nup98 is involved in binding to both Nup88 and Nup96. Autoproteolytic cleavage of the Nup98 C terminus is required for both of these binding interactions. When cleavage is blocked by a point mutation, a minimal eight amino acids downstream of the cleavage site is sufficient to prevent most binding to either Nup96 or Nup88. Thus, Nup98 interacts with both faces of the nuclear pore, a localization in keeping with its previously described nucleocytoplasmic shuttling activity.
authors.affiliation: Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia 30322, USA.
authors.forename: Eric R
authors.initials: ER
authors.lastname: Griffis
authors.forename: Songli
authors.initials: S
authors.lastname: Xu
authors.forename: Maureen A
authors.initials: MA
authors.lastname: Powers
mesh_terms: D000818:Animals; D001665:Binding Sites; D019556:COS Cells; D002467:Cell Nucleus / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism*; D004247:DNA / Q000378:metabolism; D005982:Glutathione Transferase / Q000378:metabolism; D049452:Green Fluorescent Proteins; D006367:HeLa Cells; D006801:Humans; D008164:Luminescent Proteins / Q000378:metabolism; D008856:Microscopy, Fluorescence; D016253:Microscopy, Immunoelectron; D022022:Nuclear Pore / Q000378:metabolism*; D028861:Nuclear Pore Complex Proteins / Q000096:biosynthesis* / Q000378:metabolism; D017354:Point Mutation; D011233:Precipitin Tests; D011485:Protein Binding; D017434:Protein Structure, Tertiary
chemical_list: D008164:Luminescent Proteins; C104835:NUP88 protein, human; D028861:Nuclear Pore Complex Proteins; C465451:Nup98 protein, human; C119239:nuclear pore complex protein 96; C093350:nuclear pore complex protein 98; D049452:Green Fluorescent Proteins; D004247:DNA; D005982:Glutathione Transferase