The committed step in the pathway for leucine, isoleucine, and valine catabolism is catalyzed by branchedchain α-ketoacid dehydrogenase (BCKD). This multienzyme complex is itself regulated through reversible subunit phosphorylation by a specific kinase (BCKD-kinase). Although BCKD is present in the mitochondria of all mammalian cells, BCKD-kinase has a tissue-specific pattern of expression. Various experimental, nutritional, and hormonal conditions have been used to alter the expression of BCKD-kinase, yet little is known regarding the regulation of basal BCKD-kinase expression under normal conditions including the mechanism of its tissue specificity in any organism. Here we use tissuederived cultured cells to explore the mechanisms used to control BCKD-kinase expression. Whereas the amount of BCKD-kinase protein is significantly higher in mitochondria from C2C12 myotubes than in BNL Cl.2 liver cells, gene transcription and stability of BCKD-kinase mRNA share similar properties in these two cell types. Our results show that the amount of protein synthesized is regulated at the level of translation of BCKD-kinase mRNA and that an upstream open reading frame in the 5′-untranslated region of this transcript controls its translation. The location and putative 19-residue peptide are conserved in the mouse, rat, chimpanzee, and human genes. Likewise, gene structure of mouse, chimpanzee, and human BCKD-kinase is conserved, whereas the rat gene has lost intron 9.
Tissue-specific Translation of Murine Branched-chain α-Ketoacid Dehydrogenase Kinase mRNA Is Dependent upon an Upstream Open Reading Frame in the 5′-Untranslated Region*
Published 2004 in Journal of Biological Chemistry
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- Publication year
2004
- Venue
Journal of Biological Chemistry
- Publication date
2004-10-22
- Fields of study
Biology, Medicine
- Identifiers
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- Source metadata
Semantic Scholar, PubMed
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