Figure 1. Scanning model of eukaryotic translation initiation.

Figure 1

Scanning model of eukaryotic translation initiation. The Met-tRNAiMet interacts with eIF2·GTP to form the ternary complex. The multifactor complex is an intermediate facilitating Met-tRNAiMet recruitment to the 40S ribosomal subunit, which generates the 43S complex. The eIF4 factors promote the recruitment of the 43S complex to the mRNA 5' end. The 43S complex then scans the mRNA 5' untranslated region to localize the initiator AUG (48S complex). It is not known whether the eIF4 factors participate in the scanning process. Base pairing between the Met-tRNAiMet anticodon and the AUG codon activates eIF2 GTPase, which causes the release of the bound factors. eIF1A and eIF5B interact to promote ribosomal subunits joining. 60S joining activates the GTPase activity of eIF5B, leading to its release from the 80S ribosome. The ribosome is then ready to accept the first elongating aminoacyl-tRNA in the A site. Initiation factors are labeled with their respective number, and ribosomal subunits are depicted as shaded ovals.

From: Mechanism of Translation Initiation in Eukaryotes

Cover of Madame Curie Bioscience Database
Madame Curie Bioscience Database [Internet].
Austin (TX): Landes Bioscience; 2000-2013.
Copyright © 2000-2013, Landes Bioscience.

NCBI Bookshelf. A service of the National Library of Medicine, National Institutes of Health.