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Eukaryotic protein synthesis initiation factor 2. A target for inactivation by proanthocyanidin
W Kudlicki1, W D Picking, G Kramer
1Department of Chemistry and Biochemistry, University of Texas, Austin 78712.
European Journal of Biochemistry
|May 8, 1991
Summary
Polyproanthocyanidin (PPA) from Alhagi kirgisorum inhibits protein translation by interacting with eukaryotic initiation factor 2 (eIF-2). This natural compound also blocks eIF-2 phosphorylation and protein synthesis in vitro.
Area of Science:
- Biochemistry
- Molecular Biology
- Pharmacology
Background:
- Polyproanthocyanidin (PPA) is a plant-derived phenolic polymer.
- Eukaryotic initiation factor 2 (eIF-2) is crucial for protein translation initiation.
- Protein phosphorylation plays a key role in regulating translation.
Purpose of the Study:
- To investigate the interaction between PPA and eIF-2.
- To determine the effect of PPA on in vitro translation systems.
- To explore PPA's impact on protein phosphorylation.
Main Methods:
- Isolation of PPA from Alhagi kirgisorum.
- In vitro translation assays using rabbit reticulocyte lysate.
- Protein binding and precipitation experiments.
- Enzyme assays for protein kinase activity (CK II and eIF-2 alpha kinase).
- Fluorescence spectroscopy to study PPA-protein interactions.
Main Results:
- PPA strongly interacts with and inhibits eIF-2.
- PPA blocks in vitro translation and selectively precipitates eIF-2 and regulin.
- PPA inhibits the phosphorylation of regulin by CK II and eIF-2 by eIF-2 alpha kinase.
- Fluorescence studies characterized PPA's binding to eIF-2 and regulin.
Conclusions:
- PPA is a potent inhibitor of protein translation initiation.
- PPA's mechanism involves direct interaction with eIF-2 and inhibition of its phosphorylation.
- PPA exhibits selective protein binding properties with potential therapeutic implications.