METALLOTHIONEIN-LIKE PROTEIN IN MAMMALIAN BRAIN

我们的目标是进一步描述一种 最近从大鼠脑中分离出金属硫蛋白样蛋白，并 确定其在防止重金属神经毒性方面的可能作用。 这种小分子量蛋白质(相对分子质量小于10,000)具有洗脱性 体积(Ve/Vo)为2.06，锌和铜对其合成有促进作用，但 而不是镉，而且锌刺激的蛋白质含有大量的 S[35]的半胱氨酸。据推测，这种类金属硫蛋白 蛋白质可能参与(A)锌的稳态，(B)锌的转运，(C) 在金属解毒中，或者(D)在与突触相关的事件中 功能。锌在神经化学和神经毒理学中的重要性 当人们意识到锌维持功能和/或 已知的超过235种金属酶和/或金属蛋白的结构 参与碳水化合物、脂肪、蛋白质和 核酸。此外，慢性锌流失与 小脑功能障碍、食欲减退、感觉减退、营养不良、夜间受损 视力、无脑、学习和行为模式改变。论 另一方面，在遗传性视网膜营养不良中检测到锌过量， 多发性硬化症、皮克氏病、嗜苏丹性脑白质营养不良和洛氏 综合症。大脑的金属硫蛋白样蛋白在多大程度上 这些疾病状态的改变是未知的，值得调查。这个 具体的目标是进一步表征生物化学特性。 以肝脏金属硫蛋白为标准，通过 采用Sephadex G-75凝胶过滤技术，离子 DEAE-Sephadex A-25柱交换层析，聚丙烯酰胺凝胶 非变性凝胶上的高效电泳色谱聚焦 液相色谱分析和氨基酸分析。可能的区域 金属硫蛋白样蛋白在脑内的分布 浓度不均匀，将通过放射免疫分析进行 (RIA)。此外，这种蛋白质可能的脂解活性将 被评估。此外，对这一合成的调节 金属硫蛋白样蛋白将通过培养来研究 以神经元为模型，以肝细胞为标准的系统：和 通过研究ZA++、糖皮质激素和肾上腺素、-氨基甲酸的作用 以及已知的诱导肝脏金属硫蛋白合成的激素。

Our goal is to characterize further the biochemical properties of a metallothionein-like protein recently isolated from the rat brain, and to determine its possible role in preventing neurotoxicity from heavy metals. This small molecular weight protein (Mr less than 10,000), has an elution volume (Ve/Vo) of 2.06, its synthesis is stimulated by zinc and copper but not cadmium, and the zinc-stimulated protein incorporates large quantities of [35]S-cysteine. It is hypothesized that this metallothionein-like protein may be involved (a) in zinc hemeostasis, (b) in zinc transport, (c) in metal detoxification, or perhaps (d) in events related to synaptic functions. The importance of zinc in neurochemistry and neurotoxicology becomes apparent when one realizes that zinc maintains the function and/or the structure of more than 235 metalloenzymes and/or metalloproteins known to participate in the metabolism of carbohydrates, lipids, proteins, and nucleic acids. Furthermore, chronic zinc loss is associated with cerebellar dysfunction, anorexia, hypogeusia, hyposmia, impaired night vision, anencephaly, and altered learning and behavior patterns. On the other hand, zinc excess has been detected in inherited retinal dystrophy, multiple sclerosis, Pick's disease, sudanophile leucodystrophy, and Lowe's syndrome. To what extent the brain's metallothionein-like protein is altered in these disease states is not known deserving investigation. The specific aims are to characterize further the biochemical properties of this protein by using the hepatic metallothionein as a standard and by employing techniques involving gel filtration on Sephadex G-75 columns, ion exchange chromatography on DEAE-Sephadex A-25 columns, polyacrylamide gel electrophoresis on non-denaturing gel, chromatofocusing, high performance liquid chromatography, and amino acid analysis. The possible regional distribution of metallothionein-like protein in the brain, whose zinc concentration is nonuniform, will be carried out by radioimmunoassay (RIA). In addition, the possible lipolytic activity of this protein will be assessed. Furthermore, the regulation of the synthesis of this metallothionein-like protein will be investigated by employing a culture system that uses neurons as a model and the hepatocytes as a standard: and by studying the effects of Za++, glucocorticoids and epinephrine, -ametal and hormones known to induce the synthesis of the hepatic metallothionein.