Practice question

High efficiency eukaryotic translation involves circularization of mRNA into a closed-loop topology that enhances recycling and stability. eIF4G acts as a large scaffold that simultaneously binds eIF4E attached to the 5' cap via its N-terminal domain and poly(A)-binding protein PABP bound to the 3' poly(A) tail via its C-terminal domain. The eIF4E-eIF4G-PABP interaction brings ends together, enhancing 40S subunit recycling from termination to initiation, stabilizing mRNA against deadenylation-mediated decay, and increasing affinity of eIF4F for cap. eIF2 delivers initiator tRNA and eEF2 controls translocation, neither mediating circularization directly in this model.