Affiliation:
1. The Membrane Group, The Wallenberg Laboratory, University of Uppsala, S-752 37 Uppsala, Sweden
Abstract
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, α-methylaspartate, and maltose, whereas the
trg
product appears to be a relatively ineffective transducer of signals it accepts from receptors for galactose and ribose.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
43 articles.
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