Proteomic analysis of the mammalian mitochondrial ribosome: Identification of protein components in the 28 S small subunit

Tsutomu Suzuki*, Maki Terasaki, Chie Takemoto-Hori, Takao Hanada, Takuya Ueda, Akira Wada, Kimitsuna Watanabe

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

129 Citations (Scopus)


The mammalian mitochondrial ribosome (mitoribosome) has a highly protein-rich composition with a small sedimentation coefficient of 55 S, consisting of 39 S large and 28 S small subunits. In the previous study, we analyzed 39 S large subunit proteins from bovine mitoribosome (Suzuki, T., Terasaki, M., Takemoto-Hori, C., Hanada, T., Ueda, T., Wada, A., and Watanabe, K. (2001) J. Biol. Chem. 276, 21724-21736). The results suggested structural compensation for the rRNA deficit through proteins of increased molecular mass in the mitoribosome. We report here the identification of 28 S small subunit proteins. Each protein was separated by radical-free high-reducing two-dimensional polyacrylamide gel electrophoresis and analyzed by liquid chromatography/mass spectrometry/mass spectrometry using electrospray ionization/ion trap mass spectrometer to identify cDNA sequence by expressed sequence tag data base searches in silico. Twenty one proteins from the small subunit were identified, including 11 new proteins along with their complete cDNA sequences from human and mouse. In addition to these proteins, three new proteins were also identified in the 55 S mitoribosome. We have clearly identified a mitochondrial homologue of S12, which is a key regulatory protein of translation fidelity and a candidate for the autosomal dominant deafness gene, DFNA4. The apoptosis-related protein DAP3 was found to be a component of the small subunit, indicating a new function for the mitoribosome in programmed cell death. In summary, we have mapped a total of 55 proteins from the 55 S mitoribosome on the two-dimensional polyacrylamide gels.

Original languageEnglish
Pages (from-to)33181-33195
Number of pages15
JournalJournal of Biological Chemistry
Issue number35
Publication statusPublished - 2001 Aug 31
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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