CHARACTERIZATION OF A NEW FAMILY OF PROTEIN KINASES

描述：(摘自应用摘要：)线粒体丙酮酸 脱氢酶复合体(PDC)催化氧化脱羧基 丙酮酸，决定碳水化合物代谢命运的反应。这个 哺乳动物PDC的酶活性受可逆调节 磷酸化。特定的激酶(丙酮酸脱氢酶激酶或PDK) 将其转换为只能由特定的 磷酸酶。在糖尿病、脑缺血、 代谢性酸中毒直接导致发病和死亡。 与这些情况相关的。人们普遍认为， 过度磷酸化在一定程度上是由于增强了激酶的活性。最近 该实验室提供了第一批数据，表明在人类和其他 哺乳动物体内存在多种PDK同工酶。的生理学意义 多个同工酶目前尚不清楚。到目前为止已有的结果 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。相反，可诱导的同工酶PDK4可能是主要原因 为了长期的控制。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，这反过来又有助于 高血糖症。这项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 PDK。它的主要目标是：1)确定三维结构 2)阐明丙酮酸脱氢酶的分子基础。 丙酮酸脱氢酶的催化和底物识别； 进一步明确丙酮酸调节的分子机制 脱氢酶的活性；4)表征分子间的相互作用 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，情况都很复杂。 这些目标将通过结构/功能的组合来实现 分析，生化特征，以及更多的生理 定向研究饥饿和糖尿病等条件下的同工酶。 这将使我们能够理解这种结构独特的蛋白激酶是如何 功能。它还将使我们迈出设计的第一步 同工酶特效药，可能会缓解一些症状并防止 与糖尿病、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.