TARGETING AND RETENTION OF GOLGI MEMBRANE PROTEINS

高尔基复合体在翻译后加工过程中起着核心作用 以及所有真核生物中新合成的蛋白质和脂质的分类 细胞 其最佳研究功能之一是低聚糖加工， 其精确地由表达和定位控制， 糖基转移酶和糖苷酶。 糖基化模式改变 在发育过程中，异常的糖基化模式 肿瘤细胞的转移。 高尔基复合体的分类功能 对于正常细胞功能也是至关重要的，因为蛋白质和脂质 错误的选择会导致疾病。 了解信号， 在这个细胞器中保留高尔基体常驻蛋白的机制是 了解高尔基复合体结构和功能的第一步。 早期的工作确定了重要的目标信息， 高尔基体驻留蛋白的跨膜结构域。 一个多学科 将需要一种方法来理解 识别跨膜结构域信号。 具体目标是： 1)定义高尔基体亚室定位的信号，使用 模拟了两种冠状病毒M蛋白， 高尔基复合体的表达。 两种保留介导 通过跨膜结构域和检索使用的信息， 蛋白质的胞质结构域预计有助于稳定- 状态高尔基体定位。 保留和检索机制将 研究了 2)识别和表征涉及的胞质机制 在内质网向高尔基体转运。 高效出口， 内质网是早期高尔基体定位所必需的 居民和运输机械可以发挥作用，保留， 介导浓度。 与胞质尾区相互作用的蛋白质 将鉴定模型顺式高尔基体驻留蛋白， 高尔基体定位和内质网的潜在功能， 高尔基运输将进行评估。 3)确定脂质的作用 膜蛋白在高尔基复合体中的定位。 的 高尔基体亚室的脂质组成表明， 差异可能涉及蛋白质靶向该细胞器。 将评估特定跨膜结构域之间的相互作用 使用合成肽和确定脂质组成的脂质体。 此外，高尔基体定位的居民蛋白质将是 研究后扰动不同类别的脂质在完整的 细胞

The Golgi complex plays a central role in post-translational processing and sorting of newly synthesized proteins and lipids in all eukaryotic cells. One of its best studied functions is oligosaccharide processing, which is precisely controlled by expression and localization of glycosyltransferases and glycosidases. Glycosylation patterns change during development, and aberrant glycosylation patterns may contribute to metastasis of tumor cells. The sorting function of the Golgi complex is also critical for normal cell function, since protein and lipid mistargeting can lead to disease. Understanding the signals and mechanisms that retain Golgi resident proteins in this organelle is the first step towards understanding Golgi complex structure and function. Earlier work identified important targeting information within transmembrane domains of Golgi resident proteins. A multidisciplinary approach will be required to understand the mechanism by which transmembrane domain signals are recognized. The specific aims are to: 1) Define the signals for Golgi subcompartment localization using as models two coronavirus M proteins that are targeted to opposite faces of the Golgi complex when expressed from cDNA. Both retention mediated by transmembrane domains and retrieval using information in the cytoplasmic domains of the proteins is expected to contribute to steady- state Golgi localization. Retention and retrieval mechanisms will be investigated. 2) Identify and characterize cytosolic machinery involved in endoplasmic reticulum to Golgi transport. Efficient export from the endoplasmic reticulum is required for targeting of early Golgi residents, and transport machinery may play a role in retention by mediating concentration. Proteins interacting with the cytoplasmic tail of a model cis Golgi resident protein will be identified, and their potential functions in Golgi localization and endoplasmic reticulum to Golgi transport will be assessed. 3) Determine the role of the lipid bilayer in localization of membrane proteins to the Golgi complex. The lipid composition of Golgi subcompartments suggests that discrete differences could be involved in protein targeting to this organelle. Interactions between specific transmembrane domains will be assessed using synthetic peptides and liposomes of defined lipid compositions. In addition, Golgi localization of resident proteins will be investigated after perturbation of different classes of lipids in intact cells.