Identification in the ancient protist Giardia lamblia of two eukaryotic translation initiation factor 4E homologues with distinctive functions.

ABSTRACT: Eukaryotic translation initiation factor 4E (eIF4E) binds to the m(7)GTP of capped mRNAs and is an essential component of the translational machinery that recruits the 40S small ribosomal subunit. We describe here the identification and characterization of two eIF4E homologues in an ancient protist, Giardia lamblia. Using m(7)GTP-Sepharose affinity column chromatography, a specific binding protein was isolated and identified as Giardia eIF4E2. The other homologue, Giardia eIF4E1, bound only to the m(2,2,7)GpppN structure. Although neither homologue can rescue the function of yeast eIF4E, a knockdown of eIF4E2 mRNA in Giardia by a virus-based antisense ribozyme decreased translation, which was shown to use m(7)GpppN-capped mRNA as a template. Thus, eIF4E2 is likely the cap-binding protein i

SUBMITTER: Li L 

PROVIDER: S-EPMC1140097 | biostudies-literature | 2005 May

REPOSITORIES: biostudies-literature