Eukaryotic Translation Initiation Factor 4E2 (EIF4E2)

The cap structure, which consists of a guanosine methylated at position 7 and linked via a triphosphate bridge to the 5-prime end of the mRNA, is added cotranscriptionally to all RNA polymerase II transcripts. The deduced 245-amino acid protein is 30% identical to EIF4E. Northern blot analysis detected an approximately 1.2-kb transcript in HeLa cells. Immunoblot analysis detected ubiquitous expression of a 30- to 32-kD doublet protein that was 5 to 10 times less abundant than Eif4e in rat tissues. Photochemical cross-linking and gel mobility shift analyses showed that EIF4EL3 is a cap-binding protein that uses a mechanism similar to that used by EIF4E. Immunofluorescence microscopy and immunoblot analysis demonstrated that EIF4EL3 is expressed exclusively in the cytoplasm.