MECHANISM OF ACTION OF E COLI PROTEIN EXPORT FACTORS

蛋白质定位是一个至关重要的细胞过程 蛋白质未正确定位的疾病综合征的例子 揭示细胞器故障的深刻生理后果 生物发生学。在大肠杆菌中，secB基因产物参与了 蛋白质定位和促进蛋白质输出到细胞质外b 与新生的链结合，并将它们传递到膜上，在 为跨膜转运做准备。在许多方面， SecB蛋白的功能类似于Signal执行的功能 以分泌蛋白新生链为靶点的识别颗粒 E 真核细胞中的内质网。在这篇文章中描述的研究 建议的目的是分析出口所涉及的分子细节 通过适当的细胞成分识别蛋白质，在这种情况下是 B类 蛋白质或含有SecB蛋白的蛋白质复合体，并分析 导致膜转位的后续事件。突变 影响SecB与输出蛋白之间或SecB与输出蛋白之间的相互作用 出口设备的其他部件将被隔离和表征 此外，含有SecB的蛋白质复合体将从细胞中提纯 提取并分析。这些研究的第二个焦点是隔离 影响可能执行功能的其他细胞组件的突变 与SecB的情况类似。蛋白质的多种事实和/或途径 已观察到溶酶体蛋白和分泌蛋白的定位 在真核细胞中和在原核生物中的一些出口蛋白 细胞，这项工作的目标之一是阐明其生物学作用 本地化因素的重叠。

Protein localization is a cellular process of fundamental importance and examples of disease syndromes in which proteins are not properly localized reveal the profound physiological consequences of failures in organelle biogenesis. In Escherichia coli, the secB gene product is involved in protein localization and promotes export of proteins out of the cytoplasm b associating with nascent chains and delivering them to the membrane, in preparation for translocation across the membrane. In many respects, the functions of the SecB protein resemble the functions performed by signal recognition particle in targeting nascent chains of secretory proteins to t e endoplasmic reticulum in eukaryotic cells. The studies described in this proposal are aimed at analysis of the molecular details involved in exporte protein recognition by the appropriate cellular components, in this case Se B protein or a protein complex including SecB protein, and the analysis of subsequent events which lead to membrane translocation. Mutations that affect interactions between SecB and exported proteins or between SecB and other components of the export apparatus will be isolated and characterized In addition, protein complexes that contain SecB will be purified from cell extracts and analyzed. A second focus of these studies is the isolation of mutations that affect other cellular components that may perform functions similar to those of SecB. Multiple facts and/or pathways for protein localization have been observed for lysosomal proteins and secreted protein in eukaryotic cells and for some of the exported proteins in prokaryotic cells and one of the goals of this work is to elucidate the biological role of the c\duplication of localization factors.