EMD-8190

Single-particle
5.8 Å
EMD-8190 Deposition: 17/05/2016
Map released: 13/07/2016
Last modified: 18/04/2018
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links

EMD-8190

m48S late-stage initiation complex, purified from rabbit reticulocytes lysates, displaying eIF2 ternary complex and eIF3 i and g subunits relocated to the intersubunit face

EMD-8190

Single-particle
5.8 Å
EMD-8190 Deposition: 17/05/2016
Map released: 13/07/2016
Last modified: 18/04/2018
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links
Sample Organism: Oryctolagus cuniculus, Homo sapiens
Sample: m48S late-stage initiation complex, purified from rabbit reticulocytes lysates, displaying eIF2 ternary complex and eIF3 i and g subunits relocated to the intersubunit face
Fitted models: 5k0y (Avg. Q-score: 0.141)

Deposition Authors: Simonetti A, Brito Querido J, Myasnikov AG, Mancera-Martinez E, Renaud A, Kuhn L, Hashem Y
eIF3 Peripheral Subunits Rearrangement after mRNA Binding and Start-Codon Recognition.
PUBMED: 27373335
DOI: doi:10.1016/j.molcel.2016.05.033
ISSN: 1097-2765
ASTM: MOCEFL
Abstract:
mRNA translation initiation in eukaryotes requires the cooperation of a dozen eukaryotic initiation factors (eIFs) forming several complexes, which leads to mRNA attachment to the small ribosomal 40S subunit, mRNA scanning for start codon, and accommodation of initiator tRNA at the 40S P site. eIF3, composed of 13 subunits, 8 core (a, c, e, f, h, l, k, and m) and 5 peripheral (b, d, g, i, and j), plays a central role during this process. Here we report a cryo-electron microscopy structure of a mammalian 48S initiation complex at 5.8 Å resolution. It shows the relocation of subunits eIF3i and eIF3g to the 40S intersubunit face on the GTPase binding site, at a late stage in initiation. On the basis of a previous study, we demonstrate the relocation of eIF3b to the 40S intersubunit face, binding below the eIF2-Met-tRNAi(Met) ternary complex upon mRNA attachment. Our analysis reveals the deep rearrangement of eIF3 and unravels the molecular mechanism underlying eIF3 function in mRNA scanning and timing of ribosomal subunit joining.