Synergistic activation of eIF4A by eIF4B and eIF4G
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Updated: Jun 6, 2026

Monitoring eIF4F Assembly by Measuring eIF4E-eIF4G Interaction in Live Cells
Published on: May 1, 2020
Klaus H Nielsen1, Manja A Behrens, Yangzi He
1Department of Molecular Biology, Aarhus University, Gustav Wieds Vej 10C, DK-8000 Aarhus, Denmark. khn@mb.au.dk
Abstract:
eIF4A is a key component in eukaryotic translation initiation; however, it has not been clear how auxiliary factors like eIF4B and eIF4G stimulate eIF4A and how this contributes to the initiation process. Based on results from isothermal titration calorimetry, we propose a two-site model for eIF4A binding to an 83.5 kDa eIF4G fragment (eIF4G-MC), with a high- and a low-affinity site, having binding constants KD of ∼50 and ∼1000 nM, respectively. Small angle X-ray scattering analysis shows that the eIF4G-MC fragment adopts an elongated, well-defined structure with a maximum dimension of 220 Å, able to span the width of the 40S ribosomal subunit. We establish a stable eIF4A-eIF4B complex requiring RNA, nucleotide and the eIF4G-MC fragment, using an in vitro RNA pull-down assay. The eIF4G-MC fragment does not stably associate with the eIF4A-eIF4B-RNA-nucleotide complex but acts catalytically in its formation. Furthermore, we demonstrate that eIF4B and eIF4G-MC act synergistically in stimulating the ATPase activity of eIF4A.
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