MIEF1 Microprotein Regulates Mitochondrial Translation

Biochemistry. 2018 Sep 25;57(38):5564-5575. doi: 10.1021/acs.biochem.8b00726. Epub 2018 Sep 14.


Recent technological advances led to the discovery of hundreds to thousands of peptides and small proteins (microproteins) encoded by small open reading frames (smORFs). Characterization of new microproteins demonstrates their role in fundamental biological processes and highlights the value in discovering and characterizing more microproteins. The elucidation of microprotein-protein interactions (MPIs) is useful for determining the biochemical and cellular roles of microproteins. In this study, we characterize the protein interaction partners of mitochondrial elongation factor 1 microprotein (MIEF1-MP) using a proximity labeling strategy that relies on APEX2. MIEF1-MP localizes to the mitochondrial matrix where it interacts with the mitochondrial ribosome (mitoribosome). Functional studies demonstrate that MIEF1-MP regulates mitochondrial translation via its binding to the mitoribosome. Loss of MIEF1-MP decreases the mitochondrial translation rate, while an elevated level of MIEF1-MP increases the translation rate. The identification of MIEF1-MP reveals a new gene involved in this process.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Amino Acid Sequence
  • HEK293 Cells
  • HeLa Cells
  • Humans
  • Mitochondria / genetics
  • Mitochondria / metabolism*
  • Mitochondrial Membranes / metabolism*
  • Mitochondrial Proteins / genetics
  • Mitochondrial Proteins / metabolism*
  • Open Reading Frames*
  • Peptide Elongation Factors / genetics
  • Peptide Elongation Factors / metabolism*
  • Protein Biosynthesis*
  • Sequence Homology


  • MIEF1 protein, human
  • Mitochondrial Proteins
  • Peptide Elongation Factors