Structure of the Yeast Mitochondrial Large Ribosomal Subunit

Mitoribosomes Mitochondria—found in all eukaryotic cells—have transferred most of their genes to the nuclear genome. The nuclear-localized mitochondrial genes are expressed and translated in the cytoplasm and the resulting mitochondrial proteins are imported into the mitochondria. Nevertheless, a few genes remain within mitochondria in the mitochondrial genome, and these genes are translated by mitochondrial ribosomes (mitoribosomes). Amunts et al. (p. 1485 ; see the Perspective by Kühlbrandt ) determined the structure of mitoribosomes from yeast using single-particle cryo–electron microscopy. The mitoribosome is highly diverged from the bacterial and eukaryotic ribosomes with, for example, a distinctive exit tunnel for the newly synthesized peptide, and a membrane facing protuberance that might help to anchor the mitoribosome to the mitochondrial membrane.