CHARACTERIZATION OF A NEW FAMILY OF PROTEIN KINASES

描述：（来自申请摘要：）线粒体丙酮酸 脱氢酶复合物（PDC）催化的氧化脱羧 丙酮酸，决定碳水化合物代谢命运的反应。的 哺乳动物PDC的酶活性由可逆的 磷酸化丙酮酸脱氢酶激酶（pyruvate dehydrogenase kinase，PDK） 将其转换为非活动窗体，该窗体只能由特定的 磷酸酶。在糖尿病、缺血、 而代谢性酸中毒直接导致发病和死亡 与这些条件有关。一般认为 过度磷酸化部分是由于增强的激酶活性。最近 该实验室提供的第一批数据表明，在人类和其他 哺乳动物中存在多种PDK同工酶。的生理意义 多种同工酶目前是未知的。迄今为止获得的结果 这强烈表明同工酶在功能上是不同的。同工酶 PDK2可能负责PDC的 * 短期监管 活动相比之下，诱导型同工酶PDK4可能主要负责 长期控制。它在糖尿病中的过度表达可能是导致 PDC过度磷酸化的原因，反过来，有助于 高血糖症该建议旨在进一步阐明结构， 多种同工酶的功能、调节及其生理意义 的PDK。其主要目标是：1）确定三维结构的 丙酮酸脱氢酶激酶; 2）阐明 丙酮酸脱氢酶激酶的催化和底物识别; 3） 进一步确定负责调节丙酮酸的分子机制 脱氢酶激酶活性; 4）表征分子相互作用 同工酶之间，以及同工酶和丙酮酸脱氢酶之间 在正常情况下，以及在饥饿和糖尿病下。 这些目标将通过结构/功能组合来实现 分析，生化表征，以及更多的生理 在饥饿和糖尿病等条件下的同工酶定向研究。 这将使我们了解这种结构独特的蛋白激酶 功能协调发展的这也将使我们能够迈出设计的第一步， 同工酶特异性药物，可以减轻一些症状， 与糖尿病、局部缺血和酸中毒相关的并发症。

DESCRIPTION: (From the application abstract:) The mitochondrial pyruvate dehydrogenase complex (PDC) catalyzes the oxidative decarboxylation of pyruvate, the reaction that determines the metabolic fate of carbohydrates. The enzymatic activity of the mammalian PDC is regulated by reversible phosphorylation. The specific kinase (pyruvate dehydrogenase kinase or PDK) converts it to an inactive form that can be reactivated only by a specific phosphatase. The hyperphosphorylation of PDC observed in diabetes, ischemia, and metabolic acidosis directly contributes to the morbidity and mortality associated with these conditions. It is generally believed that the hyperphosphorylation is due, in part, to enhanced kinase activity. Recently this laboratory provided the first data indicating that, in humans and other mammals there are multiple isoenzymes of PDK. The physiological significance of multiple isoenzymes is currently unknown. The results available thus far strongly suggest that the isoenzymes are functionally different. The isoenzyme PDK2 is likely to be responsible for the * short-term regulation of PDC activity. The inducible isoenzyme PDK4, in contrast, may be mainly responsible for long-term control. Its over-expression in diabetes is likely a leading cause of the hyperphosphorylation of PDC that, in turn, contributes to hyperglycemia. This proposal is aimed to further elucidate the structure, function, regulation and physiological significance of the multiple isoenzymes of PDK. Its major goals are: 1) to determine the three dimensional structure of pyruvate dehydrogenase kinase; 2) to elucidate the molecular basis for catalysis and substrate recognition by pyruvate dehydrogenase kinase; 3) to further define the molecular mechanisms responsible for regulation of pyruvate dehydrogenase kinase activity; 4) to characterize the molecular interactions between isozymes, as well as between isozymes and pyruvate dehydrogenase complex under normal conditions, as well as under starvation and diabetes. These goals will be achieved though a combination of structure/functional analysis, biochemical characterization, as well as more physiologically oriented studies of isozymes under conditions such as starvation and diabetes. This will allow us to understand how this structurally unique protein kinase functions. It will also allow us to take the first step towards the design of isoenzyme- specific drugs that may alleviate some of the symptoms and prevent complications associated with diabetes, ischemia and acidosis.