Human GTPases Associate with RNA Polymerase II To Mediate Its Nuclear Import

@article{Carr2011HumanGA,
  title={Human GTPases Associate with RNA Polymerase II To Mediate Its Nuclear Import},
  author={Cl{\'e}ment Carr{\'e} and Ramin Shiekhattar},
  journal={Molecular and Cellular Biology},
  year={2011},
  volume={31},
  pages={3953 - 3962}
}
ABSTRACT Small GTPases share a biochemical mechanism and act as binary molecular switches. One important function of small GTPases in the cell is nucleocytoplasmic transport of both proteins and RNA. Here, we show the stable association of human GPN1 and GPN3, small GTPases related to Ran, with RNA polymerase II (RNAPII) isolated from either the cytoplasmic or nuclear fraction. GPN1 and GPN3 directly interact with RNAPII subunit 7 (RPB7)/RPB4 and the C-terminal domain (CTD) of RNAPII. Depletion… 
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48 Citations

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Citation Type

A nuclear export sequence in GPN-loop GTPase 1, an essential protein for nuclear targeting of RNA polymerase II, is necessary and sufficient for nuclear export.
Biogenesis of RNA Polymerases II and III Requires the Conserved GPN Small GTPases in Saccharomyces cerevisiae
TLDR
This study shows that the nuclear import defect of iwr1Δ, but not the GPN2 or GPN3 mutant defects, is partially suppressed by fusion of a nuclear localization signal to the RNA polymerase II subunit Rpb3, and suggests that theGPN proteins function upstream of Iwr1 in RNA polymerases II and III biogenesis.
Npa3 interacts with Gpn3 and assembly factor Rba50 for RNA polymerase II biogenesis
TLDR
It is shown here that rapid degradation of each GPN protein in yeast leads to cytoplasmic accumulation of Rpb1 and defects in the assembly of RNA polymerase II, suggesting conserved functions of GPN paralogs for RNA polymerases II biogenesis as in humans.
Nuclear import of RNA polymerase II is coupled with nucleocytoplasmic shuttling of the RNA polymerase II-associated protein 2
TLDR
The results have important implications, as they indicate that RPAP2 controls gene expression by two distinct mechanisms, one that targetsRNAP II activity during transcription and the other that controls availability of RNAP II in the nucleus.
Proteomic Analysis Reveals a Role for the GTPase RPAP4/GPN1 and the Cochaperone RPAP3 in Biogenesis of All Three Nuclear RNA Polymerases
TLDR
A model in which biogenesis of RNAP I, II and III is integrated through the action of assembly and nuclear import factors is presented, suggesting that all three nuclear RNAPs may be coupled.
Rtp1p Is a Karyopherin-Like Protein Required for RNA Polymerase II Biogenesis
TLDR
Rtp1p is defined as a new component of the RNA pol II biogenesis machinery that plays roles in subunit assembly and likely in transport through the nuclear pore complex.
Npa3-Gpn3 cooperate to assemble RNA polymerase II and prevent clump of its subunits in the cytoplasm.
Structure of GPN-Loop GTPase Npa3 and Implications for RNA Polymerase II Assembly
TLDR
It is shown that Npa3 has chaperone activity and interacts with hydrophobic peptide regions of Pol II subunits that form interfaces in the assembled Pol II complex, suggesting that GPN-loop GTPases are assembly chaperones for Pol II and other protein complexes.
Human RNA polymerase II-associated protein 2 (RPAP2) interacts directly with the RNA polymerase II subunit Rpb6 and participates in pre-mRNA 3'-end formation.
TLDR
It is demonstrated that the C-terminal region of RPAP2 interacts directly with the Pol II subunit Rpb6 and participates in pre-mRNA 3'-end formation.
Npa3/ScGpn1 carboxy-terminal tail is dispensable for cell viability and RNA polymerase II nuclear targeting but critical for microtubule stability and function.
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References

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TLDR
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