title: Plant RanGAPs are localized at the nuclear envelope in interphase and associated with microtubules in mitotic cells.
abstract: In animals and yeast, the small GTP-binding protein Ran has multiple functions - it is involved in mediating (i) the directional passage of proteins and RNA through the nuclear pores in interphase cells; and (ii) the formation of spindle asters, the polymerization of microtubules, and the re-assembly of the nuclear envelope in mitotic cells. Nucleotide binding of Ran is modulated by a series of accessory proteins. For instance, the hydrolysis of RanGTP requires stimulation by the RanGTPase protein RanGAP. Here we report the complementation of the yeast RanGAP mutant rna1 with Medicago sativa and Arabidopsis thaliana cDNAs encoding RanGAP-like proteins. Confocal laser microscopy of Arabidopsis plants overexpressing chimeric constructs of GFP with AtRanGAP1 and 2 demonstrated that the fusion protein is localized to patchy areas at the nuclear envelope of interphase cells. In contrast, the cellular distribution of RanGAPs in synchronized tobacco cells undergoing mitosis is characteristically different. Double-immunofluorescence shows that RanGAPs are co-localized with spindle microtubules during anaphase, with the microtubular phragmoplast and the surface of the daughter nuclei during telophase. Co-assembly of RanGAPs with tubulin correlates with these in vivo observations. The detected localization pattern is consistent with the postulated function of plant RanGAPs in the regulation of nuclear transport during interphase, and suggests a role for these proteins in the organization of the microtubular mitotic structures.
authors.affiliation: Plant Biology Institute, Biological Research Center, H-6701 Szeged, PO Box 521, Hungary.
authors.forename: Aniko
authors.initials: A
authors.lastname: Pay
authors.forename: Katja
authors.initials: K
authors.lastname: Resch
authors.forename: Hanns
authors.initials: H
authors.lastname: Frohnmeyer
authors.forename: Erzsebet
authors.initials: E
authors.lastname: Fejes
authors.forename: Ferenc
authors.initials: F
authors.lastname: Nagy
authors.forename: Peter
authors.initials: P
authors.lastname: Nick
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000502:physiology; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000502:physiology; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000502:physiology; D002467:Cell Nucleus / Q000378:metabolism*; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D020690:GTPase-Activating Proteins / Q000235:genetics* / Q000378:metabolism; D005816:Genetic Complementation Test; D000455:Medicago sativa / Q000235:genetics / Q000502:physiology; D008870:Microtubules / Q000502:physiology*; D008938:Mitosis / Q000502:physiology*; D008969:Molecular Sequence Data; D020559:Monomeric GTP-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D009154:Mutation; D009685:Nuclear Envelope / Q000502:physiology*; D030821:Plants, Genetically Modified; D012313:RNA / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000502:physiology; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000502:physiology; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
chemical_list: C466201:AT3G63130 protein, Arabidopsis; D029681:Arabidopsis Proteins; D018076:DNA, Complementary; D020690:GTPase-Activating Proteins; C060997:RNA1 protein, S cerevisiae; C466202:RanGAP2 protein, Arabidopsis; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D012313:RNA; D020559:Monomeric GTP-Binding Proteins