Practice question

During scanning for start codon through 5' UTR, secondary structures impede 43S progression and require helicase activity. eIF4A, prototype DEAD-box RNA helicase component of eIF4F, hydrolyzes ATP to unwind RNA duplexes, melt hairpins and destabilize protein-RNA complexes in 5' leader, generating single-stranded track for 40S movement. Stimulated by accessory factors eIF4B and eIF4H, it enables processive scanning especially through GC-rich highly structured leaders of proliferation genes. Pharmacological inhibition by rocaglates clamps eIF4A on mRNA selectively blocking oncogenic translation, illustrating regulatory importance.