title: Additive and independent responses in a single receptor: aspartate and maltose stimuli on the tar protein.
abstract: The aspartate and maltose responses of E. coli are mediated through a single membrane receptor, yet the responses are independent and additive. Both stimuli cause methylation of the same 4 glutamic acid residues. More extensive methylation occurs when a cell that has adapted to one stimulus is exposed to the second, or when both stimuli are added simultaneously. The degree of methylation, as well as receptor migration on two-dimensional gels, demonstrates that only one type of protein is involved, rather than two different receptors arising from differential processing of a single gene. A conformational "push-pull" mechanism in which binding of stimulus and covalent modification, producing opposing stresses, can explain these diverse results.
authors.forename: S L
authors.initials: SL
authors.lastname: Mowbray
authors.forename: D E
authors.initials: DE
authors.lastname: Koshland
mesh_terms: D018528:ATP-Binding Cassette Transporters; D001224:Aspartic Acid / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000378:metabolism*; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins; D005796:Genes; D005798:Genes, Bacterial; D008320:Maltose / Q000378:metabolism / Q000494:pharmacology*; D058619:Maltose-Binding Proteins; D008745:Methylation; D008954:Models, Biological; D009004:Monosaccharide Transport Proteins; D009154:Mutation; D010957:Plasmids
chemical_list: D018528:ATP-Binding Cassette Transporters; D001426:Bacterial Proteins; D002352:Carrier Proteins; D029968:Escherichia coli Proteins; D058619:Maltose-Binding Proteins; D009004:Monosaccharide Transport Proteins; C461599:maltose transport system, E coli; D001224:Aspartic Acid; D008320:Maltose