InterPro domain: IPR034363

This entry represents the RNA recognition motif (RRM) found in eukaryotic translation initiation factor 3 (eIF-3), a large multisubunit complex that plays a central role in the initiation of translation by binding to the 40 S ribosomal subunit and promoting the binding of methionyl-tRNAi and mRNA.

eIF-3B is the major scaffolding subunit of eIF-3. It interacts with eIF-3 subunits A, G, I, and J [ 1 ]. eIF-3B contains an N-terminal RNA recognition motif (RRM), which is involved in the interaction with eIF-3J. The interaction between eIF-3B and eIF-3J is crucial for the eIF-3 recruitment to the 40 S ribosomal subunit [ 2 ]. eIF-3B also binds directly to domain III of the internal ribosome-entry site (IRES) element of hepatitis-C virus (HCV) RNA through its N-terminal RRM, which may play a critical role in both cap-dependent and cap-independent translation [ 3 ]. Additional research has shown that eIF-3B may function as an oncogene in glioma cells and can be served as a potential therapeutic target for anti-glioma therapy [ 4 ].

Proteins containing this domain also include eIF-3 yeast homologue subunit B (also termed Prt1) that interacts with the yeast homologues of eIF-3 subunits A(TIF32), G(TIF35), I(TIF34), J(HCR1), and E(Pci8). In yeast, eIF-3B (Prt1) contains an N-terminal RRM that is directly involved in the interaction with eIF-3A (TIF32) and eIF-3J (HCR1) [ 5 ]. In contrast to its human homologue, yeast eIF-3B (Prt1) may have potential to bind its total RNA through its RRM [ 6 ].

1. Reconstitution reveals the functional core of mammalian eIF3. EMBO J. 26, 8946-56
2. The j-subunit of human translation initiation factor eIF3 is required for the stable binding of eIF3 and its subcomplexes to 40 S ribosomal subunits in vitro. J. Biol. Chem. 279, 70-4
3. Human initiation factor eIF3 subunit b interacts with HCV IRES RNA through its N-terminal RNA recognition motif. FEBS Lett. 583, 1057-62
4. Knockdown of eukaryotic translation initiation factors 3B (EIF3B) inhibits proliferation and promotes apoptosis in glioblastoma cells. Neurol. Sci. 33
5. A subcomplex of three eIF3 subunits binds eIF1 and eIF5 and stimulates ribosome binding of mRNA and tRNA(i)Met. EMBO J. 20, 2954-65
6. Crystal structure of the RNA recognition motif of yeast translation initiation factor eIF3b reveals differences to human eIF3b. PLoS ONE 5, 3373-83