YEAST AMINO ACID PERMEASES

酵母菌的氨基酸渗透性负责运输它们的 底物进入细胞，以响应外部环境和 营养：对细胞的需求。酵母氨基酸/生长素家族 通过酵母基因组计划和 其中许多渗透的底物范围和调节已被阐明。 通过对这些渗透率的研究，越来越多的证据表明 有几组渗透率具有不同的、有限的代谢作用 牢房。例如，这些渗透率似乎可以归类为 在功能上是合成代谢的或分解代谢的，而合成代谢的特定渗透率不是 能够为它们的生长提供氨基酸底物。它的作用机制 这些高度同源的渗透率的功能区别不是 据目前所知。提出了两种可能的机制，通过这些机制， 合成代谢转运蛋白可以为蛋白质合成提供氨基酸，但不能 对于增长：发送信号或引导。这项提案中概述的实验 旨在阐明氨基酸渗透酶是否可以形成 信号途径，表明氨基酸的可用性以及 将其输送到细胞内。我们还将调查不同类型的 的渗透酶为细胞的游离氨基酸池贡献底物。 或者某些转运体是否将它们的底物‘引导’到特定的 新陈代谢的命运。这些研究将启动，重点是色氨酸及其 合成代谢渗透酶，Tat2。色氨酸摄取之所以特别有趣，是因为 有许多不寻常的表型与低色氨酸水平有关 酵母。酵母菌对色氨酸的摄取和 植物中的生长素反应。

Yeast amino acid permeases are responsible for transporting their substrates into the cell in response to the external environment and the nutritional: requirements of the cell. A family of yeast amino acid/auxin permeases has been identified through the Yeast Genome Project and the substrate range and regulation of many of these permeases has been elucidated. Through the study of these permeases, increasing evidence has accumulated that there are groups of permeases with distinct, and limited, metabolic roles in the cell. For example, it appears that these permeases can be classified as anabolic or catabolic in function and that anabolic specific permeases are not capable of supplying their amino acid substrate for growth. The mechanism of differentiation of function of these highly homologous permeases is not understood at present. Two possible mechanisms are presented by which an anabolic transporter could provide an amino acid for protein synthesis but not for growth: signaling or channeling. The experiments outlined in this proposal are designed to elucidate whether an amino acid permease can form part of the signaling pathway that indicates the availability of amino acid as well as transporting it into the cell. We will also investigate whether different types of permease contribute their substrate to the free amino acid pools of the cell or whether certain transporters 'channel' their substrate into a particular metabolic fate. These studies will be initiated focusing on tryptophan and its anabolic permease, Tat2. Tryptophan uptake is of particular interest because there are many unusual phenotypes associated with low tryptophan levels in yeast. There are also interesting parallels between yeast tryptophan uptake and auxin response in plants.