| Abstract Detail
Protein Targeting and Vesicular Trafficking Xu, Xianfeng, Morgan [1], Meulia, Tea [2], Meier, Iris [1]. The Kingdom- and Tissue-specific Anchorage of Plant RanGAP to the Nuclear Envelope Involves a Novel Family of Plant Nuclear Pore Associated Transmembrane Proteins. Ran is a multifunctional small GTPase of the Ras superfamily involved in nucleocytoplasmic transport, mitotic spindle assembly, cell cycle control, and nuclear envelope (NE) formation. Its roles are accomplished by the asymmetric distribution of its GTP- and GDP- bound forms, enabled by the specific localization of Ran accessory proteins, the Ran GTPase-activating protein RanGAP and the nucleotide exchange factor RCC1. Mammalian RanGAP1 is targeted to the NE during interphase and to the spindle and kinetochores during mitosis via a SUMOylated C-terminal domain and interaction with the nucleoporin Nup358/RanBP2. In contrast, Arabidopsis RanGAP1 is associated with the NE during interphase and the cell plate during cytokinesis, mediated by an N-terminal, plant-specific domain (WPP domain). Here, we have identified in a yeast two-hybrid screen a novel plant-specific protein that binds to the WPP domain. WPP-domain Interacting Protein 1 (WIP1) and RanGAP1 interact in vivo and co-localize at the NE and cell plate. WIP1 has two homologs in Arabidopsis (WIP2 and WIP3) with a similar domain organization of extended coiled-coil domain and C-terminal transmembrane domain. WIP1 co-localizes with a nuclear pore marker and its nuclear pore association was confirmed by immunogold-labeling. The targeting of WIP1 requires the transmembrane domain which is also sufficient for the NE (presumably nuclear pore) association. In a wip1/wip2/wip3 triple mutant, but not in single or double mutants, RanGAP1 is dislocated from the NE in undifferentiated root tip cells, while NE targeting in differentiated root cells and targeting to the cell plate remain intact. We propose that WIP family members are novel plant nuclear pore proteins involved in RanGAP1 NE anchoring in specific cell types. Our data support a separate evolution of RanGAP targeting mechanisms in different kingdoms.
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1 - The Ohio State University, Plant Cellular and Molecular Biology, 244 Rightmire Hall, 1060 Carmack Rd., Columbus, OH, 43210, USA
2 - The Ohio State University, Molecular and Cellular Imaging Center
Keywords:
Nuclear Envelope
Nuclear Pore
Ran GTPase.
Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P22007
Abstract ID:223 |
