Expression of translation initiation factor 4A from yeast and mouse in Saccharomyces cerevisiae

The eukaryotic translation initiation factor 4A (eIF-4A) plays an important role in regulating initiation. To analyze its function in yeast, we carried out a mutational analysis of the TIF1 and TIF2 genes, which encode eIF-4A. Expression of these two yeast genes has also been investigated at the transcriptional level and it has been found that both are expressed in wild-type yeast cells. Analysis of the expression of eIF-4A-beta-galactosidase fusion proteins reveals that the TIF2 gene is more highly expressed than the TIF1 gene. Interestingly, the yeast eIF-4A protein shows a high degree of amino acid sequence similarity to the mouse homologue. However, we find that the mammalian factor does not support protein synthesis in yeast either in vivo or in vitro.