Nucleotide and deduced amino acid sequence of the E1α subunit of human liver branched-chain α-ketoacid dehydrogenase

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A 1552-bp cDNA for the Elα subunit of branched-chain α-ketoacid dehydrogenase (BCKDH) was isolated from a human liver cDNA library. The cDNA contained a 1134-bp open reading frame that encoded 378 amino acid (aa) residues of the enzyme and 418 bp of 3 '-untranslated sequence. The deduced amino acid sequence of the human protein shows 96% identity with that of the rat enzyme subunit. Those 117-aa residues surrounding the phosphorylation sites are completely conserved between man and rat. BCKDH Elα showed considerable amino acid sequence similarity with pyruvate dehydrogenase Ela, particularly in the region of the two principal phosphorylation sites of these proteins. Northern blots of human liver and skin fibroblasts demonstrated a single 1.8-kb mRNA band, with a higher level of E1 α mRNA in liver than in normal fibroblasts. Fibroblasts from a patient with thiamine-responsive maple syrup urine disease (MSUD) contained an mRNA of the same size and abundance as that of normal fibroblasts. Genomic DNA from normal and MSUD fibroblasts gave the same restriction maps on Southern blots, and the gene was approximately 10-kb in size.

Original languageEnglish (US)
Pages (from-to)159-164
Number of pages6
Issue number1
StatePublished - Sep 15 1988



  • maple syrup urine disease
  • phage λ cDNA library
  • Recombinant DNA
  • sequence similarity

ASJC Scopus subject areas

  • Genetics

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