Plant RanGAPs are localized at the nuclear envelope in interphase and associated with microtubules in mitotic cells

Plant J. 2002 Jun;30(6):699-709. doi: 10.1046/j.1365-313x.2002.01324.x.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Active Transport, Cell Nucleus / physiology
  • Amino Acid Sequence
  • Arabidopsis / genetics
  • Arabidopsis / physiology
  • Arabidopsis Proteins / genetics*
  • Arabidopsis Proteins / physiology
  • Cell Nucleus / metabolism*
  • Cloning, Molecular
  • DNA, Complementary / chemistry
  • DNA, Complementary / genetics
  • GTPase-Activating Proteins / genetics*
  • GTPase-Activating Proteins / metabolism
  • Genetic Complementation Test
  • Medicago sativa / genetics
  • Medicago sativa / physiology
  • Microtubules / physiology*
  • Mitosis / physiology*
  • Molecular Sequence Data
  • Monomeric GTP-Binding Proteins / genetics*
  • Monomeric GTP-Binding Proteins / metabolism
  • Mutation
  • Nuclear Envelope / physiology*
  • Plants, Genetically Modified
  • RNA / metabolism
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / physiology
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / physiology
  • Sequence Analysis, DNA
  • Sequence Homology, Amino Acid

Substances

  • Arabidopsis Proteins
  • DNA, Complementary
  • GTPase-Activating Proteins
  • RNA1 protein, S cerevisiae
  • RanGAP1 protein, Arabidopsis
  • RanGAP2 protein, Arabidopsis
  • Recombinant Fusion Proteins
  • Saccharomyces cerevisiae Proteins
  • RNA
  • Monomeric GTP-Binding Proteins

Associated data

  • GENBANK/AF214559
  • GENBANK/AF214560
  • GENBANK/AF215731