Monoclonal antibodies against the lac carrier protein from Escherichia coli. 1. Functional studies.
Monoclonal antibodies against the lac carrier protein from Escherichia coli. 1. Functional studies.
复制标题
针对大肠杆菌 lac 载体蛋白的单克隆抗体。
DOI：
10.1021/bi00311a017
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发表时间：
1984
期刊：
影响因子：
2.9
通讯作者：
H. Kaback
中科院分区：
文献类型：
--
作者：
N. Carrasco;P. Viitanen;D. Herzlinger;H. Kaback
各种单克隆抗体对纯化的紫胶载体蛋白载体介导的乳糖转运的影响进行了研究，在右侧出膜囊泡和蛋白脂质体重建与纯化的紫胶载体蛋白。在测试的60多种单克隆抗体中，只有一种称为4 B1的抗体抑制转运。此外，抑制的性质是高度特异性的，因为抗体仅抑制涉及净质子易位的那些转运反应（即，主动转运、非能量化条件下载体介导的流入和流出以及内酯诱导的质子流入）。相反，抗体对平衡交换几乎没有影响，并且对质子电化学梯度的产生或对载体结合高亲和力配体的能力没有影响。因此，很明显，抗体在乳糖载体蛋白水平上改变了乳糖和质子易位之间的关系。当用饱和和亚饱和浓度的外部[1- 14 C]乳糖研究入口逆流时，显然抗体4 B1模拟氧化氘的作用[Viitanen，P.，加西亚，马里兰州，福斯特，D.L.，卡乔罗夫斯基，G. J.，& Kaback，H.R.（1983）Biochemistry 22，2531]。也就是说，当外部乳糖饱和时，抗体对逆流的速率或程度没有影响，但当外部乳糖低于表观Km时，抗体刺激逆流的效率。因此，抗体很可能抑制去质子化的速率或改变载体的质子化和去质子化形式之间的平衡。从抗体4 B1制备的单价Fab片段以与完整抗体定性相似的方式抑制转运。（250字处删节）
The effects of various monoclonal antibodies against purified lac carrier protein on carrier-mediated lactose transport were studied in right-side-out membrane vesicles and in proteoliposomes reconstituted with purified lac carrier protein. Out of more than 60 monoclonal antibodies tested, only one antibody, designated 4B1, inhibits transport. Furthermore, the nature of the inhibition is highly specific in that the antibody inhibits only those transport reactions that involve net proton translocation (i.e., active transport, carrier-mediated influx and efflux under nonenergized conditions, and lactone-induced proton influx). In contrast, the antibody has little effect on equilibrium exchange and no effect on generation of the proton electrochemical gradient or on the ability of the carrier to bind a high-affinity ligand. Clearly, therefore, the antibody alters the relationship between lactose and proton translocation at the level of the lac carrier protein. When entrance counterflow is studied with external [1-14C]lactose at saturating and subsaturating concentrations, it is apparent that antibody 4B1 mimics the effects of deuterium oxide [Viitanen, P., Garcia, M.L., Foster, D.L., Kaczorowski, G. J., & Kaback, H.R. (1983) Biochemistry 22, 2531]. That is, the antibody has no effect on the rate or extent of counterflow when external lactose is saturating but stimulates the efficiency of counterflow when external lactose is below the apparent Km. It seems likely, therefore, that the antibody either inhibits the rate of deprotonation or alters the equilibrium between protonated and deprotonated forms of the carrier. Monovalent Fab fragments prepared from antibody 4B1 inhibit transport in a manner that is similar qualitatively to that of the intact antibody.(ABSTRACT TRUNCATED AT 250 WORDS)