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Human eukaryotic translation initiation factor 4G (eIF4G) recruits mnk1 to phosphorylate eIF4E
S Pyronnet1, H Imataka, A C Gingras
1Department of Biochemistry and McGill Cancer Cancer Center, McGill University, 3655 Drummond Street, Montréal, Québec, H3G 1Y6 Canada.
The EMBO Journal
|January 7, 1999
Summary
Human eukaryotic translation initiation factor 4E (eIF4E) phosphorylation is modulated by Mnk1 kinase, which binds to eIF4G. This interaction is crucial for eIF4E activity in cell growth and proliferation.
Area of Science:
- Molecular Biology
- Cellular Biology
- Biochemistry
Background:
- Human eukaryotic translation initiation factor 4E (eIF4E) is a key regulator of cell growth and proliferation.
- eIF4E activity is modulated by phosphorylation, with MAPK-activated protein kinase 1 (Mnk1) identified as a potential kinase.
Purpose of the Study:
- To investigate the interaction between Mnk1 and the eIF4F complex.
- To elucidate the role of eIF4G in Mnk1-mediated phosphorylation of eIF4E.
Main Methods:
- Co-immunoprecipitation assays to study protein interactions.
- Site-directed mutagenesis to create eIF4E mutants lacking eIF4G-binding capability.
- Cellular assays to assess eIF4E phosphorylation in vivo.
Main Results:
- Mnk1 directly interacts with the C-terminal region of eIF4G, a scaffold protein in the eIF4F complex.
- Phosphorylation of an eIF4E mutant unable to bind eIF4G is significantly impaired in cells.
- Mnk1 also interacts with p97, a translational inhibitor related to eIF4G.
Conclusions:
- eIF4G serves as a docking site for Mnk1, facilitating eIF4E phosphorylation within the eIF4F complex.
- The interaction between Mnk1 and p97 suggests a mechanism for regulating eIF4E phosphorylation.
- These findings provide insights into the regulation of translation initiation and cell growth.