mRNAs containing extensive secondary structure in their 5′ non‐coding region translate efficiently in cells overexpressing initiation factor eIF‐4E.

Cellular eukaryotic mRNAs (except organellar) contain at the 5′ terminus the structure m7(5′)Gppp(5′)N (where N is any nucleotide), termed cap. Cap recognition by eukaryotic initiation factor eIF‐4F plays an important role in regulating the overall rate of translation. eIF‐4F is believed to mediate the melting of mRNA 5′ end secondary structure and facilitate 43S ribosome binding to capped mRNAs. eIF‐4E, the cap‐binding subunit of eIF‐4F, plays an important role in cell growth; its overexpression results in malignant transformation of rodent cells, and its phosphorylation is implicated in signal transduction pathways of mitogens and growth factors. The molecular mechanism by which eIF‐4E transforms cells is not known. Here, we report that overexpression of eIF‐4E facilitates the translation of mRNAs containing excessive secondary structure in their 5′ non‐coding region. This effect may represent one mechanism by which eIF‐4E regulates cell growth and transforms cells in culture.