GTPase Regulation of the Golgi Complex (Diversity Supplement 2023)

项目总结/摘要 高尔基复合体是真核细胞中近三分之一蛋白质的中央分选站， 细胞如何调节物质通过这个细胞器的流动仍然是未知的。秘密交通必须 通过高尔基体被完全糖基化和蛋白水解加工。高尔基体必须 成功地将数百种膜和内腔蛋白运输到几种不同亚细胞 目的地包括质膜、内体、溶酶体和内质网。 蛋白质和膜进出高尔基体的运输由Arf和Rab的GTP酶控制 通过募集效应蛋白来产生、运输和束缚膜而起作用的家族 囊泡和小管。全球环境基金是这些基本的GT3途径的主要调节者 （鸟嘌呤核苷酸交换因子）蛋白质，必须“决定”在何处和何时激活它们的蛋白质。 底物GTP酶。对于大多数这些GEF，我们不知道如何定位，时间， 它们的活动量受到调节。因此，我们并不完全理解 高尔基体买卖。我们的实验室致力于破译高尔基体GEF正在收听的细胞信号 以及全球环境基金如何解读这些信号。我们发现其中几个 运输途径通过蛋白质-蛋白质相互作用相互交流， 激活的GTdR积极调节另一GTdR的GEF。其中一个重要的含义是 发现不同通路的激活是协调的。尽管我们发现 调节机制的一些高尔基GEFs，其他仍然知之甚少，和 这些途径的整体分子逻辑才刚刚开始成为焦点。的首要问题 我们提出的研究计划试图回答的问题是：高尔基体的GEFs是如何做出分子决定的？ 我们将解决这个问题，通过调查每一个高尔基GEFs与广泛的一套工具，利用 生物化学重建反应，结构生物学，体内功能测定，活细胞成像，和 基因实验我们将使用生物化学方法来确定全球环境基金的确切作用 调节亚基和结构域。我们将使用结构化方法来可视化每个GEF“陷入 在其GT3上进行核苷酸交换的行为。基于假设产生的突变体 生物化学和结构实验产生的，然后将在体内研究，以确定 干扰特定相互作用和域的后果。我们将使用无偏见的蛋白质组学和 遗传学方法来揭示未知GEFs的身份，并发现未知的调节因子。 高尔基GEFs。我们将使用已建立的细胞生物学方法来确定生理 监管机制的重要性。总之，体内和体外的综合结果 实验将使我们能够确定GEF用于定位其作用部位的机制， 确定其底物并调节其活性。因此，我们将定义高尔基体GEFs如何感知 并整合信号，我们将获得它们如何协同工作的整体视图，我们将揭示 支撑高尔基体功能的分子逻辑

Project Summary/Abstract The Golgi complex is the central sorting station for nearly a third of all proteins in eukaryotic cells, but how cells regulate the flow of material through this organelle remains unknown. Secretory traffic must pass through the Golgi to be fully glycosylated and proteolytically processed. The Golgi must successfully traffic hundreds of membrane and lumenal proteins to several different sub-cellular destinations including the plasma membrane, endosomes, lysosomes, and the endoplasmic reticulum. Protein and membrane traffic into and out of the Golgi is controlled by GTPases of the Arf and Rab families that function by recruiting effector proteins to generate, transport, and tether membrane vesicles and tubules. The master regulators of these essential GTPase pathways are the GEF (guanine-nucleotide exchange factor) proteins that must “decide” where and when to activate their substrate GTPases. For most of these GEFs, we do not know how the localization, timing, and magnitude of their activity is regulated. Therefore, we do not fully understand the molecular logic of Golgi trafficking. Our lab has focused on deciphering what cellular signals the Golgi GEFs are listening to, and how the GEFs interpret these signals. We have discovered that several of these GTPase trafficking pathways communicate with each other through protein-protein interactions in which an activated GTPase positively regulates the GEF of another GTPase. One important implication of this finding is that activation of the distinct pathways are coordinated. Although we have uncovered regulatory mechanisms for some of the Golgi GEFs, the others remain poorly understood, and the overall molecular logic of these pathways is only beginning to come into focus. The primary question our proposed research program seeks to answer is: How do the Golgi GEFs make molecular decisions? We will address this question by investigating each of the Golgi GEFs with a broad set of tools, utilizing biochemical reconstitution reactions, structural biology, in vivo functional assays, live-cell imaging, and genetic experiments. We will use biochemical approaches to determine the precise roles of GEF regulatory subunits and domains. We will use structural approaches to visualize each GEF “caught in the act” of performing nucleotide exchange on its GTPase. Mutants generated based on hypotheses arising from biochemical and structural experiments will then be investigated in vivo to determine the consequences of perturbing specific interactions and domains. We will use unbiased proteomic and genetic approaches to reveal the identity of unknown GEFs and to discover unknown regulators of the Golgi GEFs. We will use established cell biological approaches to determine the physiological importance of the regulatory mechanisms. Taken together, the combined results of in vivo and in vitro experiments will enable us to determine the mechanisms the GEFs use to localize to their site of action, identify their substrate, and regulate their activity. Therefore, we will define how the Golgi GEFs sense and integrate signals, we will obtain a holistic view of how they work together, and we will uncover the molecular logic underpinning how the Golgi functions.