Eukaryotic translation initiation factor 4E family member 3 (EIF4E3)

Eukaryotic translation initiation factor 4E family member 3 (EIF4E3) is a cap-binding protein in the EIF4E family, structurally distinct from canonical EIF4E1 by its unique cap-recognition mode and inability to bind eIF4G efficiently[1][2]. EIF4E3 is highly conserved among vertebrates and differs from EIF4E1 by having a Cys–Trp pair instead of two aromatic residues at the cap-binding site[1]. EIF4E3 specifically binds the 7-methylguanosine (m^7G) cap of mRNA, but with significantly lower affinity (10–40 fold) than EIF4E1[1][2]. Unlike EIF4E1, which promotes translation and oncogenic transformation, EIF4E3 acts as a **tumor suppressor** by competing for capped transcripts, repressing their translation, and thereby antagonizing growth-promoting pathways[1][3]. EIF4E3 is expressed in a limited subset of cells, notably hematopoietic cells, and its loss has been associated with the progression of acute myeloid leukemia and certain solid tumors such as oral cancers[1]. It does not efficiently interact with the canonical translation initiation factors (e.g., eIF4G, 4E-BP1), rendering it less likely to form an active ribosome recruitment complex under basal conditions[2]. However, during specific cellular stresses such as hypoxia or mTOR pathway inhibition, EIF4E3 can be incorporated into alternative eIF4F complexes (e.g., with eIF4G3) to selectively modulate translation[3]. There are no known drugs that directly target EIF4E3, and its primary mechanism of action as a therapeutic target would be through modulating its expression or altering its competitive interaction with EIF4E1. Reduced EIF4E3 levels may serve as a biomarker for certain malignancies; however, there are currently no widely used clinical biomarkers derived from EIF4E3 status[1]. Loss of EIF4E3 may result in increased susceptibility to oncogenic transformation, marking it as a putative tumor suppressor and a potential, though as yet untargeted, therapeutic target[1][3].

Other names

Eukaryotic translation initiation factor 4E type 3eIF-4E type 3eIF-4E3eIF4E type 3eIF4E-3MGC39820

Inhibition of oncogenic translation by sequestration of capped mRNAs Negative regulation of eIF4E1 activity by cap-binding competition