ИСТИНА

Mitochondrial translation apparatus is finely tuned for the synthesis of limited set of proteins, resulting in highly specialized organellar ribosomes and noticeable deviations from the canonical set of translation factors. The combination of phylogenetic analysis with in vivo complementation tests allowed identification of the yeast protein Aim23p as mitochondrial ortholog of bacterial IF3 (4). The interaction of Aim23p with the yeast mitochondrial ribosome was previously shown in two independent studies. The first study detected Aim23p in samples of GFP-tagged mitochondrial ribosomes upon immunoprecipitation with anti-GFP antibodies (3). Further evidence came from work where yeast mitochondrial lysates were separated on sucrose gradients and Aim23p was found in the fractions containing mitochondrial ribosomes (5). Both pieces of evidence indicate that Aim23p interacts with yeast mitochondrial ribosome, but do not strictly show that and Aim23p was not found in high resolution cryo-EM structures of yeast mitochondrial ribosomes or their large subunits. To better understand the interaction of Aim23p with yeast mitochondrial ribosomes we have exploited two independent experimental setups and provide solid biochemical confirmation the previous observations that Aim23p interacts with the small subunit of mitochondrial ribosome, both in vivo and in vitro.