CONTROL OF GAMMA AMINOBUTYRIC ACID SYNTHESIS

γ-氨基丁酸合成的控制

• 批准号: 2244431
• 负责人: DAVID L MARTIN
• 金额: $ 15.48万
• 依托单位: WADSWORTH CENTER
• 依托单位国家: 美国
• 财政年份: 1980
• 资助国家: 美国
• 起止时间: 1980-08-01 至 1999-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2244431
• 关键词: adenosine triphosphate; apoenzymes; aspartate; brain metabolism; enzyme inhibitors; enzyme mechanism; enzyme structure; enzyme substrate; gamma aminobutyrate; glutamate decarboxylase; glutamates; high performance liquid chromatography; isozymes; laboratory rat; neurotransmitter biosynthesis; phosphates; phosphorus; protein sequence; psychopharmacology; pyridoxal phosphate; radionuclides; radiotracer; synaptosomes

Pharmacological manipulation of neurotransmitter metabolism has been a powerful tool in the treatment of nervous and mental diseases. Many insights in psychopharmacology have resulted from our basic knowledge of neurotransmitter systems. The long-term goal of this research is to elucidate the control mechanisms that regulate the synthesis of gamma-aminobutyric acid (GABA), a major neurotransmitter in brain. Current evidence suggests that glutamate decarboxylase (GAD), the enzyme responsible for GABA synthesis, is regulated at two levels. At one level, the amount of holoGAD (the active form containing bound cofactor, pyridoxal-5'-phosphate) appears to be controlled by a cycle of inactivation (apoGAD formation) and reactivation (holoGAD formation) which is under allosteric control by ATP and Pi. This mechanism is supported by enzymatic and neurochemical studies. At the second level, GAD activity may be regulated by the interconversion of different forms of the enzyme each of which has different regulatory properties. We have recently discovered multiple forms of GAD that appear to differ in the extent to which they undergo the cycle of inactivation and reactivation (level one regulation). These forms could result from several mechanisms; for example, from interconversion of the forms (eg. by phosphorylation) in response to changes in neuronal activity, or from maturation of GAD as it moves from the ribosome to the synapse. They could also result from the combination of non-identical subunits as does lactate dehydrogenase or could be different forms found in different cell types or brain regions. We plan to examine these possibilities by studies of the purified enzyme and studies with brain slices, synaptosomes and in vivo. We plan a structural comparison of the forms (e.g. to determine subunit structure, possibility of phosphorylation, etc.). Such studies will show how the forms differ and thus provide important information on how they could be interconverted. We also plan studies with synaptosomes, and brain slices to determine if depolarization alters that inactivation/reactivation cycle of each form or causes the conversion of one form to another. We plan to determine if the relative amounts of the forms differ among brain regions or during development. Finally, we plan to compare the regulatory and structural differences among the forms from human brain.

神经递质代谢的药理操作一直是 治疗神经和精神疾病的强大工具。 许多 心理药理学的见解是我们对 神经递质系统。 这项研究的长期目标是 阐明调节合成的控制机制 γ-氨基丁酸（GABA），大脑中的主要神经递质。 当前的 有证据表明谷氨酸脱羧酶（GAD），酶 负责GABA合成，在两个级别上进行调节。 在一个级别， 全息（含有结合辅助因子的活性形式）的量， 吡ido虫5'-磷酸）似乎是由失活的循环控制的 （Apogad形成）和重新激活（全息形成） ATP和PI的变构控制。 这种机制得到了酶促的支持 和神经化学研究。 在第二层，GAD活动可能是 由不同形式的酶的互连调节 具有不同的法规特性。 我们最近发现了 多种形式的GAD似乎在它们的程度上有所不同 经历失活和重新激活的循环（第一级调节）。 这些形式可能是由几种机制造成的。例如，来自 形式的相互转换（例如，通过磷酸化）响应于 神经元活动的变化，或从GAD的成熟中移动而移动的变化 突触的核糖体。 它们也可能是由组合造成的 与乳酸脱氢酶一样 在不同的细胞类型或大脑区域中发现的不同形式。 我们计划 通过研究纯化酶和研究来检查这些可能性 带有脑切片，突触体和体内。 我们计划一个结构 形式的比较（例如，为了确定亚基结构，可能性 磷酸化等）。 这样的研究将表明表格如何不同，并且 因此，提供有关如何互换的重要信息。 我们 还计划突触小体和大脑切片的研究以确定是否是否 去极化改变了每种形式或 导致一种形式转换为另一种形式。 我们计划确定是否 大脑区域或期间的相对数量不同 发展。 最后，我们计划比较监管和结构 人脑的形式之间的差异。