Busch, J.D. et al. Cell Rep. 29, 1728–1738.e9 (2019)

Mitoribosomes—specialized ribosomes in the mitochondria—synthesize proteins upon which mitochondria depend. Should mitoribosomes go awry, a number of mitochondrial disorders can ensue; most studies on the subject have however been done in yeast and human cell lines. To study the composition and function of mitoribosomes in vivo, researchers from the Karolinska Institute in Sweden and the Max-Planck Institute for Biology of Aging in Germany developed the MitoRibo-Tag mouse.

These knockin mice express a FLAG-tag on mitoribosomal protein ML62; this protein tag enables mitoribosome tracking across different tissues, allowing researchers to see where and how these RNA/protein complexes interact with different molecules. In the paper, published in Cell Reports, the researchers use MitoRibo-Tag mice to identify a number of regulatory factors, as well as the identity of an orphan protein and its role in efficient mitochondrial translation.