STRUCTURE AND ACTIVITY OF MEMBRANE TRANSPORT PROTEINS

拟议调查的总体目标是测试 假设看似不同的运输蛋白有共同的 由一个共同的结构决定的行动机制。膜 转运蛋白在正常人体新陈代谢中起着重要作用 真核细胞和原核细胞，是几种疾病的病原体 并确定各种药物的治疗效果。 因此，了解底物识别的基本过程 并在分子水平上进行运输，最终能够 改变这些过程，在食品中具有重要的潜在意义 生产、生物技术和医药。具体来说，我们建议使用 定点突变和基因融合技术与联合应用 用膜转运试验来检验这一假说 几个看似不同的转运体依赖于 高度保守的氨基酸残基，在不同的 运输蛋白，包括四环素抗性蛋白(Tet) 和几个革兰氏阴性细菌的糖转运体。Tet和糖 转运蛋白在预测12个膜跨度方面是相似的。 区域和某些主题的保护，这些主题产生了重要的 统计检验中的相似程度。三度空间 这些蛋白质的结构很可能与相对 细微的结构差异是他们认识到 不同的底物，意味着基本相似的分子机制。

The overall objective of the proposed investigation is to test the hypothesis that seemingly dissimilar transport proteins have a common mechanism of action which is dictated by a common structure. Membrane transport proteins serve essential functions in the metabolism of normal eucaryotic and procaryotic cells, are causative agents in several disease states, and determine the therapeutic efficacy of various drugs. Therefore, understanding the fundamental processes of substrate recognition and transport at the molecular level, and then ultimately being able to alter these processes, has significant potential importance in food production, biotechnology and medicine. Specifically, we propose to use site-directed mutagenesis and gene fusion techniques in combination with membrane transport assays to test the hypothesis that the activities of several seemingly diverse transporters are dependent upon a subset of highly conserved amino acid residues which are conserved in various transport proteins, including the tetracycline resistance proteins (Tet) and several sugar transporters of gram negative bacteria. Tet and sugar transporters are alike in the prediction of twelve membrane-spanning regions and in the conservation of certain motifs which yield significant levels of similarity in statistical tests. The three dimensional structures of these proteins are likely to be similar with relatively subtle structural differences that account for their recognition of different substrates, implying fundamentally similar molecular mechanisms.