PROTEIN TRANSLOCATION IN YEAST

拟议研究的主要目标是了解 正确的蛋白质被靶向和转位的机制 穿过简单真核生物的内质网膜 酿酒酵母。目前的模型表明，至少有 两条平行的靶向和转位途径，一条依赖SRP和 合作翻译，另一种是独立于SRP的翻译后翻译。 通过基因和生物化学方法的结合，我们的目标是 确定催化常见反应的基因产物 两条路径或其中一条或另一条路径所独有的，并理解其 分子功能、调节和生理重要性。 具体地说，i)我们将描述SRP和SRP的机制(S) SRP受体协调核糖体和核糖体之间的相互作用 转位组分形成核糖体膜连接。Ii)我们 将描述与SRP无关的中介组件 路径。我们将分析这些成分是如何作用于选择蛋白质的 进入这一途径，以及它们如何发挥作用将蛋白质靶向内质网 薄膜。三)我们将确定“适应”的分子基础， 允许细胞改善蛋白质转运的生理反应 当依赖SRP的途径被破坏时。 我们希望了解这一过程的哪些方面是酵母和 哪些方面可以推广到其他真核细胞和细菌。 最终，我们希望通过基因和生物化学的结合 通过这种方法，我们将在机械论层面上理解所有 蛋白质转运机制的细胞成分 对易位以及对那些 是可调节的。

The primary objective of the proposed research is to understand the mechanism by which the correct proteins are targeted to and translocated across the endoplasmic reticulum membrane in the simple eucaryote Saccharomyces cerevisiae. Current models suggest that there are at least two parallel targeting and translocation pathways, one SRP-dependent and co-translational, the other SRP-independent and post-translational. Through the combination of genetic and biochemical approaches, we aim to identify the gene products that catalyze the reactions that are common to both pathways or unique to one or the other and to understand their molecular function, regulation and physiological importance. Specifically, i) we will characterize the mechanism(s) by which SRP and SRP receptor coordinate the interactions between the ribosome and translocon components to form the ribosome membrane junction. ii) We will characterize the components that mediate the SRP-independent pathway. We will analyze how these components function to select proteins into this pathway, and how they function to target proteins to the ER membrane. iii) We will determine the molecular basis of "adaptation", the physiological response that allows cells to improve protein translocation when the SRP-dependent pathway is disrupted. We wish to learn which aspects of the process are unique to yeast and which aspects can be generalized to other eucaryotic cells and bacteria. Ultimately, we hope that through a combined genetic and biochemical approach, we will understand, at a mechanistic level, the function of all of the cellular constituents of the protein translocation machinery that are essential for translocation, as well as the function of those that are modulatory.