ROLE OF TRYPTOPHAN ON HEPATIC PROTEIN SYNTHESIS

这项调查感兴趣的是探索单个基本要素是如何 氨基酸，特别是L-色氨酸，影响蛋白质的代谢。 肝脏。在我们实验室早些时候的报告中，我们描述了 L-色氨酸快速刺激肝多聚核糖体聚集和 蛋白质合成。这一效应似乎与 转录和转录后控制。早期研究 在细胞和亚细胞水平上已经揭示了L-色氨酸 作用于肝细胞核(核膜)刺激增强 核质转位基因的最新研究结果表明 核膜上有一个特定的色氨酸结合部位 大鼠肝脏的。这个kDa糖蛋白受体对L-色氨酸有 经过提纯和鉴定。我们计划进一步刻画 KDa糖蛋白的组成、活性结构和功能 纯化为肝核膜色氨酸结合蛋白。 这将使用纯化的大鼠肝核膜进行 色氨酸结合蛋白以及使用克隆的融合蛋白。自.以来 色氨酸快速刺激肝细胞核多聚(A)聚合酶活性 因为我们已经确定了这种酶和 色氨酸受体蛋白，我们计划定义 在这两者之间。我们认为色氨酸的受体结合和 色氨酸对聚(A)聚合酶活性的增强作用 在色氨酸诱导的刺激中的重要和至关重要的成分 肝脏蛋白质合成。这些信息可以提供基本的洞察力，如 一种重要的饮食成分，如L-色氨酸， 可能在哺乳动物肝脏蛋白质代谢中起到调节作用。

This investigation is interested in exploring how a single essential amino acid, specifically L-tryptophan, affects protein metabolism in the liver. In earlier reports from our laboratory, we have described that L-tryptophan rapidly stimulates hepatic polyribosomal aggregation and protein synthesis. This effect appears to be related to alterations in both transcriptional and posttranscriptional controls. Earlier studies at the cellular and subcellular levels have revealed that L-tryptophan acts on the hepatic nucleus (nuclear membrane) to stimulate enhanced nucleocytoplasmic translocation of mRNA Recent findings have demonstrated that there is a specific tryptophan-binding site on the nuclear envelopes of rat liver. This 64 kDa glycoprotein receptor for L-tryptophan has been purified and characterized. We plan to further characterize (composition, active structure and function) the 64 kDa glycoprotein purified as the hepatic nuclear envelope tryptophan binding protein. This will be conducted using purified rat hepatic nuclear envelope tryptophan binding protein as well as using cloned fusion protein. Since tryptophan rapidly stimulates hepatic nuclear poly(A)polymerase activity and since we have determined a close association between this enzyme and the tryptophan receptor protein, we plan to define the relationship between the two. We consider the receptor binding of tryptophan and the enhancement of poly(A)polymerase activity due to tryptophan to be important and vital components in the tryptophan-induced stimulation of hepatic protein synthesis. Such information may offer basic insight as to how an important dietary component, as exemplified by L-tryptophan, may play a regulatory role in mammalian liver protein metabolism.