Structural highlights
Function
[EIF3B_HUMAN] Component of the eukaryotic translation initiation factor 3 (eIF-3) complex, which is required for several steps in the initiation of protein synthesis. The eIF-3 complex associates with the 40S ribosome and facilitates the recruitment of eIF-1, eIF-1A, eIF-2:GTP:methionyl-tRNAi and eIF-5 to form the 43S preinitiation complex (43S PIC). The eIF-3 complex stimulates mRNA recruitment to the 43S PIC and scanning of the mRNA for AUG recognition. The eIF-3 complex is also required for disassembly and recycling of post-termination ribosomal complexes and subsequently prevents premature joining of the 40S and 60S ribosomal subunits prior to initiation.[1]
Publication Abstract from PubMed
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 A 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-tRNAiMet 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.
eIF3 Peripheral Subunits Rearrangement after mRNA Binding and Start-Codon Recognition.,Simonetti A, Brito Querido J, Myasnikov AG, Mancera-Martinez E, Renaud A, Kuhn L, Hashem Y Mol Cell. 2016 Jun 29. pii: S1097-2765(16)30197-6. doi:, 10.1016/j.molcel.2016.05.033. PMID:27373335[2]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Chaudhuri J, Chakrabarti A, Maitra U. Biochemical characterization of mammalian translation initiation factor 3 (eIF3). Molecular cloning reveals that p110 subunit is the mammalian homologue of Saccharomyces cerevisiae protein Prt1. J Biol Chem. 1997 Dec 5;272(49):30975-83. PMID:9388245
- ↑ 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. Mol Cell. 2016 Jun 29. pii: S1097-2765(16)30197-6. doi:, 10.1016/j.molcel.2016.05.033. PMID:27373335 doi:http://dx.doi.org/10.1016/j.molcel.2016.05.033
