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An ATP-dependent activity that releases RanGDP from NTF2
Masami Yamada1, Iain W Mattaj, Yoshihiro Yoneda
1European Molecular Biology Laboratory, Meyerhofstrasse 1, D-69117 Heidelberg, Germany.
The Journal of Biological Chemistry
|May 25, 2004
Summary
Researchers discovered a new ATP-dependent activity that releases GDP from Ran, a protein crucial for nuclear transport. This novel RanGDF activity, involving NTF2, suggests a new regulatory mechanism in the RanGDP/GTP cycle.
Area of Science:
- Cellular Biology
- Molecular Biology
- Biochemistry
Background:
- The small GTPase Ran is essential for eukaryotic cellular processes like nuclear transport and spindle formation.
- NTF2, a RanGDP-binding protein, aids RanGDP translocation and stabilizes it against nucleotide exchange.
Purpose of the Study:
- To identify and characterize a novel activity that stimulates GDP release from Ran in the presence of NTF2.
- To elucidate the role of ATP and other factors in this RanGDP dissociation process.
Main Methods:
- Investigated GDP dissociation from Ran using NTF2.
- Assessed the effect of hydrolyzable and non-hydrolyzable ATP analogues on GDP release.
- Compared the novel activity with RanGDP dissociation catalyzed by RCC1.
Main Results:
- Identified a novel ATP-dependent activity that stimulates GDP release from Ran in the presence of NTF2.
- This activity functions as a RanGDP dissociation inhibitor (GDI) displacement factor (RanGDF), with NTF2 acting as the GDI.
- The activity is enhanced by ATP and inhibited by non-hydrolyzable ATP analogues, and stimulated by protein phosphatase inhibitors, suggesting phosphorylation-dependent regulation.
Conclusions:
- A novel ATP-dependent RanGDF activity, utilizing NTF2 as the GDI, has been identified.
- This pathway likely plays a regulatory role in the RanGDP/GTP cycle, impacting nuclear transport and other cellular functions.