Figure 1. Model of cap dependent translation initiation.

eIF4F binds to the m⁷G cap structure via the cap-binding protein eIF4E. eIF4G is a scaffold protein which also binds to the RNA helicase eIF4A and eIF3, which in turn recruits the 43S pre-initiation complex (PIC). The PIC consists of the 40S ribosomal subunit, eIF2-GTP-Met-tRNAi and several other initiation factors, which are indicated. eIF4A melts the secondary structure in the 5′-UTR and the PIC scans the mRNA until it encounters the AUG start codon where the 60S subunit joins, followed by peptide chain synthesis. eIF4G also binds to PABP which brings about the circularization of the mRNA allowing for efficient ribosome recycling.