YEAST AMINO ACID PERMEASES

酵母氨基酸渗透酶负责运输它们的 底物响应于外部环境而进入细胞， 营养：细胞的需要。酵母氨基酸/生长素家族 已通过酵母基因组计划和 已经阐明了许多这些渗透酶的底物范围和调节。 通过对这些渗透层的研究，越来越多的证据表明， 有几组渗透酶具有不同的、有限的代谢作用， 牢房例如，似乎这些渗透性可以被分类为 合成代谢或分解代谢的功能，合成代谢特异性渗透酶不 能够为它们的生长提供氨基酸底物。的机理 这些高度同源的透膜酶的功能分化不是 目前理解。提出了两种可能的机制， 合成代谢转运蛋白可以为蛋白质合成提供氨基酸， 对于增长：信号或引导。本提案中概述的实验 旨在阐明氨基酸通透酶是否可以形成蛋白质的一部分， 信号通路，指示氨基酸的可用性以及 将其运送到细胞中。我们还将调查不同类型的 的通透酶将其底物贡献给细胞的游离氨基酸库 或者某些转运蛋白是否将其底物“引导”到特定的 代谢命运这些研究将集中在色氨酸及其 合成代谢通透酶，Tat 2。色氨酸摄取特别令人感兴趣，因为 有许多不寻常的表型与低色氨酸水平有关， 酵母酵母对色氨酸的摄取与 植物的生长素反应。

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.