Koman A, Harayama S, Hazelbauer G L
J Bacteriol. 1979 Jun;138(3):739-47. doi: 10.1128/jb.138.3.739-747.1979.
We determined the content of galactose-glucose-, maltose-, and ribose-binding proteins in cells of Escherichia coli K-12 grown in a variety of media and also measured the respective transport and chemotactic activities that depend on those binding proteins. Correlation of the level of induction of a particular binding protein with the extent of tactic activity mediated by that protein indicates that the magnitude of the tactic response to a particular stimulating compound is a direct function of the number of receptors per cell. In contrast, comparison of the magnitudes of response to substances recognized by independent receptors indicates that some stimulus-receptor complexes are more effective in eliciting tactic responses than are others. Thus, the magnitude of response to any particular stimulating compound is a function both of the number of receptors per cell and of the effectiveness of the stimulus-receptor complex. Considerations of available information about the tactic response to maltose suggest that the effectiveness of a stimulus-receptor complex is related to the transducer with which the receptor interacts. The tar product appears to be a relatively effective transducer of the signals it accepts from receptors for aspartate, alpha-methylaspartate, and maltose, whereas the trg product appears to be a relatively ineffective transducer of signals it accepts from receptors for galactose and ribose.
我们测定了在多种培养基中生长的大肠杆菌K-12细胞内半乳糖-葡萄糖结合蛋白、麦芽糖结合蛋白和核糖结合蛋白的含量，还测量了依赖于这些结合蛋白的各自的转运和趋化活性。特定结合蛋白的诱导水平与该蛋白介导的趋化活性程度之间的相关性表明，对特定刺激化合物的趋化反应强度是每个细胞受体数量的直接函数。相比之下，对由独立受体识别的物质的反应强度进行比较表明，一些刺激-受体复合物在引发趋化反应方面比其他复合物更有效。因此，对任何特定刺激化合物的反应强度既是每个细胞受体数量的函数，也是刺激-受体复合物有效性的函数。关于对麦芽糖趋化反应的现有信息的思考表明，刺激-受体复合物的有效性与受体相互作用的转导器有关。tar产物似乎是其从天冬氨酸、α-甲基天冬氨酸和麦芽糖受体接受的信号的相对有效的转导器，而trg产物似乎是其从半乳糖和核糖受体接受的信号的相对无效的转导器。
