COMPARATIVE PHYSIOLOGY OF MEMBRANE TRANSPORT

建议对其生理生化机制进行研究。 采用比较和进化的方法进行膜转运。我们 假设最早的细胞利用了“质子经济”(初级 质子泵产生质子梯度，用于 质子-衬底共运输和其他过程)。在后来的进化中，一个 “钠经济”一词最复杂的表述是在 动物细胞。建议对联合运输系统进行比较，利用 质子(大肠杆菌的乳糖载体)利用钠离子进行共转运 (大肠杆菌的脯氨酸载体)。此外，我们计划研究一项 代表使用以下两种方式之一的中间运营商 共转运的质子或钠(大肠杆菌的蜜糖载体)。突变者 会被分离出来，表现出糖专一性或阳离子的变化 承认。我们打算克隆每一种运输工具的突变基因 蛋白质和用Sanger双脱氧核苷酸测定DNA序列 方法。日本血吸虫变异氨基酸序列的比较 载体蛋白和运输生理的改变将有助于 将三维结构与功能联系起来。 第二个项目涉及细胞比较生理学的研究。 音量调节。与没有细胞壁的动物细胞微生物一样 (如鸡毒支原体)必须持续泵出氯化钠和 由于胶体渗透和Donnan而扩散到细胞内的水 力量。建议研究氯化钠的离子机理。 鸡败血杆菌的挤出物及其与动物用挤出物的比较 细胞。

It is proposed to study the physiological and biochemical mechanism of membrane transport using a comparative and evolutionary approach. We postulate that the earliest cell utilized a "proton economy" (primary proton pumps generated a proton gradient which was used for proton-substrate cotransport and other processes). Later in evolution a "sodium economy" developed and found its most sophisticated expression in animal cells. It is proposed to compare cotransport systems utilizing protons (lactose carrier of E. coli) with cotransport utilizing sodium ion (proline carrier of E. coli). In addition we plan to study a representative of the intermediate class of carriers that utilize either protons or sodium for cotransport (melibiose carrier of E. coli). Mutants will be isolated which show changes in sugar specificity or catiom recognition. We intend to clone the mutant gene for each of the transport proteins and determine the DNA sequence by the Sanger dideoxynucleotide method. A comparison between the altered amino acid sequence of the carrier protein and the altered physiology of transport will help to correlate three dimensional structure with function. A second project involves a study of the comparative physiology of cell volume regulation. As with animal cells microorganisms without cell walls (such as Mycoplasma gallisepticum) must continuously pump out the NaCl and water that diffuse into the cell as a result of colloid osmotic and Donnan forces. It is proposed to investigate the ionic mechanism for NaCl extrusion from M. gallisepticum and compare it with that used by animal cells.