Anchorage of plant RanGAP to the nuclear envelope involves novel nuclear-pore-associated proteins

Curr Biol. 2007 Jul 3;17(13):1157-63. doi: 10.1016/j.cub.2007.05.076.

Abstract

The Ran GTPase controls multiple cellular processes including nucleocytoplasmic transport, spindle assembly, and nuclear envelope (NE) formation [1-4]. Its roles are accomplished by the asymmetric distribution of RanGTP and RanGDP enabled by the specific locations of the Ran GTPase-activating protein RanGAP and the nucleotide exchange factor RCC1 [5-8]. Mammalian RanGAP1 targeting to the NE and kinetochores requires interaction of its sumoylated C-terminal domain with the nucleoporin Nup358/RanBP2 [9-14]. In contrast, Arabidopsis RanGAP1 is associated with the NE and cell plate, mediated by an N-terminal, plant-specific WPP domain [15-18]. In the absence of RanBP2 in plants, the mechanism for spatially sequestering plant RanGAP is unknown. Here, Arabidopsis WPP-domain interacting proteins (WIPs) that interact with RanGAP1 in vivo and colocalize with RanGAP1 at the NE and cell plate were identified. Immunogold labeling indicates that WIP1 is associated with the outer NE. In a wip1-1/wip2-1/wip3-1 triple mutant, RanGAP1 is dislocated from the NE in undifferentiated root-tip cells, whereas NE targeting in differentiated root cells and targeting to the cell plate remain intact. We propose that WIPs are novel plant nucleoporins involved in RanGAP1 NE anchoring in specific cell types. Our data support a separate evolution of RanGAP targeting mechanisms in different kingdoms.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Arabidopsis / metabolism*
  • Arabidopsis / ultrastructure
  • Arabidopsis Proteins / metabolism*
  • Cell Differentiation
  • GTPase-Activating Proteins / metabolism*
  • Molecular Sequence Data
  • Nuclear Pore / metabolism*
  • Nuclear Pore / ultrastructure
  • Nuclear Proteins / metabolism*
  • Plant Roots / metabolism
  • Plant Roots / ultrastructure
  • Protein Conformation

Substances

  • Arabidopsis Proteins
  • GTPase-Activating Proteins
  • Nuclear Proteins
  • RanGAP1 protein, Arabidopsis

Associated data

  • GENBANK/AY045697
  • GENBANK/AY735734
  • GENBANK/AY735735
  • GENBANK/BT003145