Effect of Dietary Protein on the Liver Content and Subunit Composition of the Branched-Chain α-Ketoacid Dehydrogenase Complex

Y. Zhao, K. M. Popov, Y. Shimomura, N. Y. Kedishvili, J. Jaskiewicz, M. J. Kuntz, J. Kain, B. Zhang, Robert Harris

Research output: Contribution to journalArticle

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Abstract

Levels of expression of two subunits of the liver branched-chain α-ketoacid dehydrogenase complex in response to extremes of dietary protein intake (50% versus 0% protein diet) were determined by quantitative immunoblotting. Dietary protein deficiency decreased the amount of E1α protein to a greater extent than E2 protein. The ratio of E1α to E2 was below 1 in the liver of animals starved for protein and above 1 in the liver of animals fed the high-protein diet. Supplementation of the 0% protein diet with 5% leucine (but not 5% valine) had the same effect as the 50% protein diet. The extremes of dietary protein also resulted in a divergent pattern of expression of the mRNAs for the subunits of the complex. The E1β message showed the expected corollary of being greater in the liver of the high-protein-fed rats than the no-protein-fed rats. In contrast, the E2 message was not affected by the two extremes of dietary protein and the E1α message was greater in the liver of the no-protein-fed rats than the high-protein-fed rats. Thus, coordinate regulation of gene expression of the subunits of the complex does not occur in response to dietary protein. Post-transcriptional regulatory mechanisms most likely determine the amount of the complex and the ratio of its subunits. The decrease in E1α/E2 protein ratio that occurs in dietary protein deficiency may increase sensitivity of the complex to phosphorylation-mediated inhibition by branched-chain α-ketoacid dehydrogenase kinase.

Original languageEnglish
Pages (from-to)446-453
Number of pages8
JournalArchives of Biochemistry and Biophysics
Volume308
Issue number2
DOIs
StatePublished - Feb 1994

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3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)
Dietary Proteins
Liver
Chemical analysis
Proteins
Nutrition
Rats
Diet
Protein Deficiency
Animals
Phosphorylation
Valine
Gene Expression Regulation
Immunoblotting
Gene expression
Leucine

ASJC Scopus subject areas

  • Molecular Biology
  • Biophysics
  • Biochemistry

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Effect of Dietary Protein on the Liver Content and Subunit Composition of the Branched-Chain α-Ketoacid Dehydrogenase Complex. / Zhao, Y.; Popov, K. M.; Shimomura, Y.; Kedishvili, N. Y.; Jaskiewicz, J.; Kuntz, M. J.; Kain, J.; Zhang, B.; Harris, Robert.

In: Archives of Biochemistry and Biophysics, Vol. 308, No. 2, 02.1994, p. 446-453.

Research output: Contribution to journalArticle

Zhao, Y. ; Popov, K. M. ; Shimomura, Y. ; Kedishvili, N. Y. ; Jaskiewicz, J. ; Kuntz, M. J. ; Kain, J. ; Zhang, B. ; Harris, Robert. / Effect of Dietary Protein on the Liver Content and Subunit Composition of the Branched-Chain α-Ketoacid Dehydrogenase Complex. In: Archives of Biochemistry and Biophysics. 1994 ; Vol. 308, No. 2. pp. 446-453.
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