Mitochondrial Ribosome Recycling Factor (MRRF)

The termination of protein synthesis requires the action of several auxiliary factors. In bacteria, ribosome-recycling factor (Rrf) is essential for the release of ribosomes from the mRNA at the stop codon. Mitochondria perform protein synthesis using a translation system that has some features reminiscent of prokaryotic translation and other features that are unique. Zhang and Spremulli (1998) identified human ESTs encoding mitochondrial ribosome-recycling factor (MRRF). They assembled the complete MRRF coding sequence using ESTs. Sequence analysis of the deduced 263-amino acid MRRF protein indicated that it is likely localized in the mitochondria; however, MRRF does not have a clear cleavage signal for removal of the signal peptide. Human MRRF shares approximately 25 to 30% amino acid sequence identity with bacterial RRFs.