STRUCTURE AND PROCESSING OF TRYPANOSOME VARIANT ANTIGENS

感染人类和动物的锥虫有主要的医学 以及对赤道非洲的兽医后果。失灵了 免疫系统消除锥虫感染在很大程度上 可归因于卵巢锥体的独特机制 抗原性变异。每个锥虫都被一个表面覆盖着 由紧密堆积的单分子层组成的涂层，约为1000万 变异表面大家族中单个成员的分子 糖蛋白(VSG)。这项建议的目的是研究 VSGS的羧基末端平移后修饰 布氏锥虫，存在疏水肽尾巴 在初级VSG mRNA翻译产物上，被切割并 取而代之的是一种复杂的葡聚糖肌醇磷脂，它锚定 VSG至表面膜。变量的问题 VSG连接的糖脂的半乳糖化将通过 在具有多个TH的糖脂上延伸结构 VSG的直接前兆的预期特征- 连接的糖脂将被确定，起诉之前 将VSG链接作为实验设计的模型 方法论。有迹象表明，多肽作为一种模型 实验设计和方法。有迹象表明， 肽的裂解和糖脂的附着发生在一个共同的 在内质网的协调反应，但进一步 多糖侧链的加工可能发生在高尔基体中 仪器。将开发无细胞系统，使用 锥虫微体组分，其中的细节 可以研究改性反应。这样做的另一个目的是 建议研究糖脂部分在VSG中的作用 分泌、功能、周转和释放。概念性和 对这些方面的实验贡献可以从 相似的翻译后意识的不断扩大 几种哺乳动物蛋白质的修饰。因为锥虫 将糖脂结合到10%的蛋白质(VSG)上，他们可能会 表示在其中探索 可能对所有真核生物都很重要的修饰途径 细胞。VSG释放酶，一种糖磷脂酰肌醇- 特异性磷脂酶C(GPI-PLC)，将进一步鉴定。 将进行进一步的特异性研究，其亚细胞 地点将被确定，其活动的监管将由 效应物和抑制物将被确定。GPI-PLC基因 将被克隆和测序，用于研究其生物合成， 监管，并便利相应的特征描述 哺乳动物的酶。

Human and animal-infective trypanosomes have major medical and veterinary consequences for equatorial Africa. Failure of the immune system to eliminate trypanosome infections is largely attributable to the Salivarian trypanosomes' unique mechanism for antigenic variations. Each trypanosome is covered by a surface coat consisting of a closely packed monolayer of about ten million molecules of a single member of a large family of variant surface glycoproteins (VSGs). The aim of this proposal is to study the carboxy-terminal post-translational modification of the VSGs of Trypanosoma brucei, whereby a hydrophobic peptide tail, present on the primary VSG mRNA translation product, is cleaved and replaced by a complex glycan inositol phospholipid, which anchors VSG to the surface membrane. The question of variable galactosylation of the VSG-linked glycolipid will be resolved by extending structural at a glycolipid having several of teh characteristic expected of an immediate precursor of the VSG- linked glycolipid will be determined, suing the previously characterized VSG-linked as a model for experimental design and methodology. There are indications that peptide as a model for experimental design and methodology. There are indications that peptide cleavage and glycolipid attachment occur in a co- ordinated reaction at the endoplasmic reticulum, but that further processing of the glycan side-chain may occur in the Golgi apparatus. Cell-free systems will be developed, using trypanosome microsomal fractions, in which details of the modification reaction can be investigated. A further aim of this proposal is to investigate the role of the glycolipid moiety in VSG secretion, function, turnover and release. Conceptual and experimental contributions to these aspects can be expected from the expanding awareness of similar post-translational modification of several mammalian proteins. Since trypanosomes attach glycolipid to 10% of their protein (the VSG), they may represent the ideal model in which to explore some aspects of a modification pathway that may be important to all eukaryotic cells. The VSG-releasing enzyme, a glycan-phosphatidylinositol- specific phospholipase C (GPI-PLC), will be further characterized. Further specificity studies will be performed, its subcellular location will be determined, and the regulation of its activity by effectors and inhibitors will be determined. The GPI-PLC gene will be cloned and sequenced, for studies of its biosynthesis, regulation, and to facilitate characterization of the corresponding mammalian enzyme.