Membrane Transport of Melibiose by Escherichia coli

研究的目的是阐明作用机制 载体分子在底物-阳离子共转运系统中的 在细菌E.大肠杆菌，特别关注黑二糖 载体 阳离子缺乏的自发突变体的分离 识别和糖识别之后将分析 它们在膜运输中的生理异常。 的 载体中氨基酸取代的生理效应 分子，特别是在跨膜区域，将被 考察 预期使用定点诱变提供 对“螺旋发夹”假说的实验检验， 将蜜二糖载体插入膜中。 其他研究 将采用多克隆抗体，试图确定 载体的假定“环”区域的取向 膜的 小分子如糖和无机离子 通过富含脂质的细胞膜进入细胞是一种 基本利益和重要性的问题;主动运输 通常涉及特定的载体分子， 是其中之一--黑二糖载体--这是本研究的重点 research. 该项目的目标是了解分子 允许其特异性结合的载体分子的方面 一些分子而不是另一些分子， 以允许糖共转运的方式， 阳离子在适当的方向。 //

The goal of the research is to elucidate the mechanism of action of the carrier molecule in a substrate-cation cotransport system in the bacterium E. coli, with specific focus on the melobiose carrier. Isolation of spontaneous mutants deficient in cation recognition and sugar recognition will be followed by analysis of their physiological abnormalities in membrane transport. The physiological effects of amino-acid substitution in the carrier molecule, particularly in membrane-spanning regions, will be examined. Use of site-directed mutagenesis is expected to provide an experimental test of the "helical hairpin" hypothesis for insertion of the melobiose carrier into membranes. Other studies will employ polyclonal antibodies in an attempt to determine the orientation of presumed "loop" regions of the carrier in the membrane. The means whereby small molecules such as sugars and inorganic ions gain entrance to cells through the lipid-rich cell membrane is a matter of fundamental interest and importance; active transport across membranes often involves specific carrier molecules and it is one of these--the melobiose carrier--that is the focus of this research. The goal of the project is to understand the molecular aspects of the carrier molecule that permit it to bind specifically to some molecules and not others, and to be inserted into cell membranes in a manner that permits cotransport of sugars and cations in appropriate directions. //