Sec7 Domain Arf Exchange Factors In Membrane Traffic

膜流量中的 Sec7 域 Arf 交换因素

• 批准号: 6541339
• 负责人: Catherine L Jackson
• 金额: --
• 依托单位: EUNICE KENNEDY SHRIVER NATIONAL INSTITUTE OF CHILD HEALTH & HUMAN DEVELOPMENT
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/6541339
• 关键词: ADP ribosylation; Golgi apparatus; Saccharomyces cerevisiae; brefeldin A; fungal proteins; guanine nucleotide exchange factors; guanosinetriphosphatases; intermolecular interaction; intracellular transport; membrane activity; microorganism culture; protein transport

A distinguishing feature of eukaryotic cells is their internal membrane organization. Internal membrane stuctures are highly dynamic and their integrity and maintenance are dependent upon continual membrane trafficking and protein transport. The small GTPase ARF (ADP-Ribosylation Factor) plays an essential role in multiple steps of protein transport. The GDP/GTP cycle of ARF results in changes in both lipid and protein composition of membranes, thus modulating membrane structure. The best-studied role of ARF is recruitment of cytosolic coat complexes onto membranes, which can deform membranes to produce transport intermediates and concentrate cargo proteins into these transport carriers. A newly-discovered class of ARF effectors is lipid modifying enzymes such as phosphatidylinositol-4-phosphate 5-kinase. ARF relies on a guanine nucleotide exchange factor (GEF) to become activated. Dr. Catherine L. Jackson?s laboratory was the first to identify an ARF GEF, named Gea1p (for Guanine-nucleotide Exchange on ARF) in S. cerevisiae. There are now a dozen ARF GEF proteins characterized to date. They all share a region of approximately 200 amino acids (the "Sec7 domain") that is homologous to a domain of the Sec7p protein of S. cerevisiae, involved in secretion. The Sec7 domain alone is necessary and sufficient to catalyze GDP/GTP exchange on ARF in vitro. We are investigating the in vivo and in vitro functions of the Sec7 domains of three ARF GEFs in S.cerevisiae, Gea1p, Gea2p, and Sec7p, and two Sec7 orthologues in mammalian cells, BIG1 and BIG2. A number of interacting partners of the Sec7 domains of Gea1/2p, Sec7p an BIG2 have been identified. We are investigating both the physical properties of these interactions and their physiological roles. A second major project is the identification of membrane-binding determinants in the Sec7 domain proteins. All of these proteins are peripherally associated with membranes, and it is not known whether membrane interaction is mediated by direct association with lipids or through protein-protein interaction. Interestingly, one direct binding partner of Gea2p is a transmembrane-domain protein, so this interaction is being explored for a potential membrane-targeting role.

真核细胞的一个显著特征是它们的内部膜组织。内膜结构是高度动态的，其完整性和维持依赖于连续的膜运输和蛋白质运输。小GTP酶ARF（ADP-核糖基化因子）在蛋白质转运的多个步骤中起着至关重要的作用。ARF的GDP/GTP循环导致膜的脂质和蛋白质组成的变化，从而调节膜结构。ARF的最佳研究作用是将胞质外壳复合物募集到膜上，其可以使膜变形以产生转运中间体并将货物蛋白浓缩到这些转运载体中。一类新发现的ARF效应子是脂质修饰酶，如磷脂酰肌醇-4-磷酸5-激酶。ARF依赖于鸟嘌呤核苷酸交换因子（GEF）被激活。凯瑟琳·L.博士杰克逊？的实验室是第一个鉴定出ARF GEF的，命名为Gea 1 p（ARF上的鸟嘌呤核苷酸交换）。啤酒。迄今为止，已经鉴定了十几种ARF GEF蛋白。它们都共有一个约200个氨基酸的区域（“Sec 7结构域”），该区域与S.酿酒酵母，参与分泌。单独的Sec 7结构域在体外催化ARF上的GDP/GTP交换是必要的和足够的。 我们正在研究在酿酒酵母中的三个ARF GEFs，Gea 1 p，Gea 2 p和Sec 7 p，以及在哺乳动物细胞中的两个Sec 7直系同源物，BIG 1和BIG 2的Sec 7结构域的体内和体外功能。已经鉴定了Gea 1/2 p、Sec 7 p和BIG 2的Sec 7结构域的许多相互作用伴侣。我们正在研究这些相互作用的物理特性及其生理作用。第二个主要项目是确定Sec 7结构域蛋白中的膜结合决定簇。所有这些蛋白质都与膜外周相关，并且尚不清楚膜相互作用是通过与脂质直接相关还是通过蛋白质-蛋白质相互作用介导的。有趣的是，Gea 2 p的一个直接结合伴侣是跨膜结构域蛋白，因此正在探索这种相互作用的潜在膜靶向作用。