Zhang B, Crabb D W, Harris R A
Department of Biochemistry, Indiana University School of Medicine, Indianapolis 46223.
Gene. 1988 Sep 15;69(1):159-64. doi: 10.1016/0378-1119(88)90390-3.
A 1552-bp cDNA for the E1 alpha subunit of branched-chain alpha-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 E1 alpha showed considerable amino acid sequence similarity with pyruvate dehydrogenase E1 alpha, 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 alpha 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.
从人肝脏cDNA文库中分离出支链α-酮酸脱氢酶（BCKDH）E1α亚基的1552bp cDNA。该cDNA包含一个1134bp的开放阅读框，编码该酶的378个氨基酸残基以及418bp的3'-非翻译序列。推导的人蛋白质氨基酸序列与大鼠酶亚基的序列有96%的同一性。人及大鼠中围绕磷酸化位点的117个氨基酸残基完全保守。BCKDH E1α与丙酮酸脱氢酶E1α显示出相当程度的氨基酸序列相似性，尤其是在这些蛋白质的两个主要磷酸化位点区域。人肝脏和皮肤成纤维细胞的Northern印迹显示出一条单一的1.8kb mRNA条带，肝脏中E1α mRNA的水平高于正常成纤维细胞。硫胺素反应性枫糖尿症（MSUD）患者的成纤维细胞所含mRNA的大小和丰度与正常成纤维细胞相同。正常和MSUD成纤维细胞的基因组DNA在Southern印迹上给出相同的限制性图谱，该基因大小约为10kb。
