Eukaryotic translation initiation factor 4E-3

UniProtKB accession:  O61955

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UniProtKB description:  Recognizes and binds the 7-methylguanosine-containing mRNA cap during an early step in the initiation of protein synthesis and facilitates ribosome binding by inducing the unwinding of the mRNAs secondary structures. All 5 eIF4E proteins bind monomethyl cap structures. Only ife-1, ife-2 and ife-5 bind trimethyl cap structures which result from trans-splicing. Translation of trimethyl cap structure mRNAs may be regulated by intracellular redox state; disulfide bonds change the width and depth of the cap-binding cavity determining selectivity to mRNA caps. Ife-3 is essential for viability. Component of the pid-1 and tost-1 variants of the PETISCO complexes, which have roles in the biogenesis of a class of 21 nucleotide PIWI-interacting RNAs (piRNAs) that possess a uracil residue at the 5'-end (also called 21U-RNAs) and embryogenesis, respectively (PubMed:31147388, PubMed:31216475). Within the pid-1 variant of the PETISCO complex binds to capped 21U-RNA precursor molecules, possibly playing a role in the processing of the 5' end of the molecules to promote binding of other complex components such as pid-3 (PubMed:31147388). However, it is not essential for the biogenesis of 21U-RNAs by itself (PubMed:31147388). Within the tost-1 variant of the PETISCO complex binds to splice leader SL1 RNA fragments to possibly play a role in their processing (PubMed:31147388).