title: The importin-beta P446L dominant-negative mutant protein loses RanGTP binding ability and blocks the formation of intact nuclear envelope.
abstract: Three of the four independently induced Ketel(D) dominantnegative female sterile mutations that identify the Drosophila importin-beta gene, originated from a C4114--> T transition and the concurrent replacement of Pro446 by Leu (P446L). CD spectroscopy of representative peptides with Pro or Leu in the crucial position revealed that upon the Pro-->Leu exchange the P446L mutant protein loses flexibility and attains most likely an open conformation. The P446L mutation abolishes RanGTP binding of the P446L mutant form of importin-beta protein and results in increased RanGDP binding ability. Notably, the P446L mutant importin-beta does not exert its dominant-negative effect on nuclear protein import and has no effect on mitotic spindle-related functions and chromosome segregation. However, it interferes with nuclear envelope formation during mitosis-to-interphase transition, revealing a novel function of importin-beta.
authors.affiliation: The University of Szeged, Faculty of Medicine, Department of Biology, Somogyi B. u. 4, H-6720 Szeged, Hungary.
authors.forename: Gyula
authors.initials: G
authors.lastname: Timinszky
authors.forename: László
authors.initials: L
authors.lastname: Tirián
authors.forename: Ferenc T
authors.initials: FT
authors.lastname: Nagy
authors.forename: Gábor
authors.initials: G
authors.lastname: Tóth
authors.forename: András
authors.initials: A
authors.lastname: Perczel
authors.forename: Zsuzsanna
authors.initials: Z
authors.lastname: Kiss-László
authors.forename: Imre
authors.initials: I
authors.lastname: Boros
authors.forename: Paul R
authors.initials: PR
authors.lastname: Clarke
authors.forename: János
authors.initials: J
authors.lastname: Szabad
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000502:physiology; D000595:Amino Acid Sequence; D000818:Animals; D002453:Cell Cycle / Q000502:physiology; D002843:Chromatin / Q000378:metabolism; D002942:Circular Dichroism; D029721:Drosophila Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000033:anatomy & histology / Q000196:embryology*; D005260:Female; D005456:Fluorescent Dyes / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D007247:Infertility, Female / Q000235:genetics; D034882:Lamins / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D009685:Nuclear Envelope / Q000378:metabolism*; D010455:Peptides / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D016415:Sequence Alignment; D008941:Spindle Apparatus / Q000378:metabolism; D019076:Transgenes; D028961:beta Karyopherins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020931:ran GTP-Binding Protein / Q000378:metabolism*
chemical_list: D002843:Chromatin; D029721:Drosophila Proteins; D005456:Fluorescent Dyes; C424162:Fs(2)Ket protein, Drosophila; D034882:Lamins; D010455:Peptides; D011993:Recombinant Fusion Proteins; D028961:beta Karyopherins; D020931:ran GTP-Binding Protein