Eukaryotic Translation Initiation Factor 4B (EIF4B)

Eukaryotic translation initiation factor 4B (eIF4B) facilitates the binding of mRNA to the 43S preinitiation complex, which consists of the 40S ribosomal subunit bound to a ternary complex of eIF2, GTP, and Met-tRNA stabilized by eIF3. eIF4F, a heterotrimeric protein, binds to the mRNA cap structure and, in combination with eIF4B, is thought to unwind the secondary structure in the 5-prime untranslated region of the mRNA to facilitate ribosome binding. Besides its RNA-binding activity, eIF4B stimulates the ATPase and RNA helicase activities of eIF4A, one component of eIF4F. Overexpression of eIF4B in mammalian cells inhibited translation. Southern blot analysis suggested that there are multiple eIF4B genes or pseudogenes in the human genome.