Internal ribosome entry site of encephalomyocarditis virus RNA is unable to direct translation in Saccharomyces cerevisiae.

To evaluate the potential of the encephalomyocarditis virus (EMCV) internal ribosome entry site (IRES) to promote efficient expression of foreign genes in the yeast, S. cerevisiae, we have constructed E. coli-yeast shuttle vectors in which the EMCV 5' non-coding region was fused to the reporter gene, human prothymosin alpha. Efficiency of translation of corresponding RNA transcripts in mammalian cell-free systems was highly dependent on the sequence context and/or position of the initiation codon. No translation of these IRES-dependent mRNAs occurred in S. cerevisiae.