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Updated: Aug 7, 2026

Toeprinting Analysis of Translation Initiation Complex Formation on Mammalian mRNAs
Published on: May 10, 2018
A conserved HEAT domain within eIF4G directs assembly of the translation initiation machinery
J Marcotrigiano1, I B Lomakin, N Sonenberg
1Laboratories of Molecular Biophysics, The Rockefeller University, New York, NY 10021, USA.
Abstract:
The X-ray structure of the phylogenetically conserved middle portion of human eukaryotic initiation factor (eIF) 4GII has been determined at 2.4 A resolution, revealing a crescent-shaped domain consisting of ten alpha helices arranged as five HEAT repeats. Together with the ATP-dependent RNA helicase eIF4A, this HEAT domain suffices for 48S ribosomal complex formation with a picornaviral RNA internal ribosome entry site (IRES). Structure-based site-directed mutagenesis was used to identify two adjacent features on the surface of this essential component of the translation initiation machinery that, respectively, bind eIF4A and a picornaviral IRES. The structural and biochemical results provide mechanistic insights into both cap-dependent and cap-independent translation initiation.
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