Mitochondrial translation initiation

Stable Identifier
Homo sapiens
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Translation initiates with the mitochondrial mRNA binding the 28S subunit:MTIF3 (28S subunit:IF-3Mt, 28S subunit:IF3mt) complex together with MTIF2:GTP (IF-2Mt:GTP, IF2mt:GTP) (reviewed in Christian and Spremulli 2012, Kuzmenko et al. 2014). As inferred from bovine homologs, the 28S subunit, 39S subunit, and 55S holoribosome associate with the matrix-side face of the inner membrane and the translation products are inserted into the inner membrane as translation occurs (Liu and Spremulli 2000). Mitochondrial mRNAs have either no untranslated leader or short leaders of 1-3 nucleotides, with the exception of the 2 bicistronic transcripts, RNA7 and RNA14, which have overlapping orfs that encode ND4L/ND4 and ATP8/ATP6 respectively.. Binding of N-formylmethionine-tRNA to the start codon results in a stable complex between the mRNA and the 28S subunit while absence of a start codon at the 5' end of the mRNA causes the mRNA to slide though the 28S subunit and eventually dissociate. The 39S subunit then binds the 28S subunit:mRNA complex, GTP is hydrolyzed, and the initiation factors MTIF3 and MTIF2:GDP dissociate.
Literature References
PubMed ID Title Journal Year
23954798 Mitochondrial translation initiation machinery: conservation and diversification

Tenson, T, Kamenski, P, Hauryliuk, V, Levitskii, S, Zenkin, N, Atkinson, GC, Kuzmenko, A

Biochimie 2014
10887179 Interaction of mammalian mitochondrial ribosomes with the inner membrane

Liu, M, Spremulli, L

J. Biol. Chem. 2000
22172991 Mechanism of protein biosynthesis in mammalian mitochondria

Spremulli, LL, Christian, BE

Biochim. Biophys. Acta 2012
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