Crossroads at translation initiation: the long and the short of a short and a long 5’ transcript leader and the eukaryotic initiation factor eIF4E3

Abstract

Translation is the biochemical process by which messenger RNAs are used as template for the synthesis of proteins by the ribosome. The first step of translation, initiation, requires the ribosome to find a start codon on the mRNA. Its efficiency depends on the Kozak context and length of the 5’ transcript leader (5’ TL). In eukaryotes, it also requires a series of translation factors (eIF). One of them is the cap binding protein, eIF4E, and is actually part of a family of three in mammals whose the third member, eIF4E3, has never been extensively studied. In this work, we have been focusing on eIF4E3 and tested if the protein was expressed from its short 5’ TL. From this we asked what happens to the eIF4E-cap interaction in the translation of short 5’ TL. Finally, we studied the function of eIF4E3 and determined a possible role in stress conditions.