Shimomura Y, Obayashi M, Murakami T, Harris R A
Department of Bioscience, Nagoya Institute of Technology, Nagoya, Japan.
Curr Opin Clin Nutr Metab Care. 2001 Sep;4(5):419-23. doi: 10.1097/00075197-200109000-00013.
Branched-chain alpha-keto acid dehydrogenase kinase is responsible for the inactivation and phosphorylation of the branched-chain alpha-keto acid dehydrogenase complex, the enzyme that catalyses the committed step of branched-chain amino acid catabolism. The activity of the branched-chain alpha-keto acid dehydrogenase complex is inversely correlated with kinase activity, suggesting that the relative activity of the kinase is the primary regulator of the activity of the complex. It has been shown that kinase activity and expression are affected by nutritional states imposed by low-protein diet feeding, starvation, diabetes, and exercise. Evidence has also been presented that certain hormones, particularly insulin, glucocorticoid, thyroid hormone and female sex hormones, affect the activity and expression of the kinase. The findings indicate that nutritional and hormonal control of the activity and expression of branched-chain alpha-keto acid dehydrogenase kinase provides an important means of control of the activity of the branched-chain alpha-keto acid dehydrogenase complex, with inactivation serving to conserve branched-chain amino acids for protein synthesis in some situations and activation serving to provide carbon for gluconeogenesis in others.
支链α-酮酸脱氢酶激酶负责使支链α-酮酸脱氢酶复合体失活并使其磷酸化，该复合体是催化支链氨基酸分解代谢关键步骤的酶。支链α-酮酸脱氢酶复合体的活性与激酶活性呈负相关，这表明激酶的相对活性是该复合体活性的主要调节因子。研究表明，激酶活性和表达受低蛋白饮食喂养、饥饿、糖尿病和运动所导致的营养状态影响。也有证据表明某些激素，特别是胰岛素、糖皮质激素、甲状腺激素和雌性激素，会影响该激酶的活性和表达。这些发现表明，对支链α-酮酸脱氢酶激酶活性和表达的营养及激素调控为控制支链α-酮酸脱氢酶复合体的活性提供了重要手段，在某些情况下使该复合体失活有助于保留支链氨基酸用于蛋白质合成，而在其他情况下使其激活则有助于为糖异生提供碳源。
