Translation termination: new factors and insights.

In eukaryotes, translation termination requires two eukaryotic release factors, eRF1 and eRF3. eRF1 is required for recognition of the stop codon and eRF3 supports the polypeptide chain release in a GTP dependent manner. Recently, several new players in translation termination have been identified. The DEAD-box RNA helicase Dbp5 has been shown to support eRF1 in stop codon recognition, possibly by proper placement of the release factor on the termination codon. Upon its dissociation from eRF1, Dbp5 allows the entry of the second termination factor eRF3 into the complex. Further, the Dbp5 interacting protein Gle1 and its co-factor inositol hexakisphosphate (IP 6) have been shown to participate in the termination process. Dbp5 and Gle1 are well known for their function in mRNA export from the nucleus to the cytoplasm. Most interestingly, also the ATP binding cassette (ABC) protein Rli1, which requires the mitochondrial and cytosolic Fe/S protein biogenesis machineries for its assembly, has recently been shown to function in translation termination and recycling of the ribosomes. Rli1 physically and genetically interacts with both, eRF1 and eRF3. Together, all of these novel termination factors modulate in association with the release factors more accurate stop codon recognition and these findings broaden our knowledge about the final steps in translation.