Harris R A, Popov K M, Zhao Y, Shimomura Y
Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis 46202-5122.
J Nutr. 1994 Aug;124(8 Suppl):1499S-1502S. doi: 10.1093/jn/124.suppl_8.1499S.
Catabolism of the branched-chain amino acids is regulated in part at the step catalyzed by the branched-chain alpha-ketoacid dehydrogenase complex. Previous work suggests both short-term and long-term control mechanisms are involved in regulation of the kinase responsible for phosphorylation and inactivation of the branched-chain alpha-ketoacid dehydrogenase complex. Recent work of this laboratory has focused on the isolation, characterization and molecular cloning of the branched-chain alpha-ketoacid dehydrogenase kinase. The cDNA obtained encodes the complete mature protein of 412 amino acids among with a mitochondrial entry sequence of 30 amino acids. Analysis of the deduced amino acid sequence revealed little similarity with eukaryotic Ser/Thr protein kinases. However, the kinase shows considerable sequence similarity with prokaryotic histidine protein kinases. The availability of this cDNA will facilitate gene expression studies of this important regulatory enzyme for the branched-chain alpha-ketoacid dehydrogenase complex.
支链氨基酸的分解代谢部分是在由支链α-酮酸脱氢酶复合体催化的步骤中进行调节的。先前的研究表明，短期和长期控制机制都参与了对负责使支链α-酮酸脱氢酶复合体磷酸化并使其失活的激酶的调节。本实验室最近的工作集中在支链α-酮酸脱氢酶激酶的分离、表征和分子克隆上。获得的cDNA编码412个氨基酸的完整成熟蛋白，其中有一个30个氨基酸的线粒体导入序列。对推导的氨基酸序列的分析显示，它与真核丝氨酸/苏氨酸蛋白激酶几乎没有相似性。然而，该激酶与原核组氨酸蛋白激酶显示出相当大的序列相似性。这个cDNA的获得将有助于对支链α-酮酸脱氢酶复合体这一重要调节酶进行基因表达研究。
