title: Active uptake of glutamate in vesicles of Halobacterium salinarium.
abstract: Uptake of glutamate into vesicles of Halobacterium salinarium has been studied during respiration and in the nonrespiring state. Uptake requires respiration or a minimum gradient in NaCl, which is consistent with an Na+ symport mechanism for uptake, as proposed for H. halobium. By replacing KCl or NaCl by choline chloride, it has been possible to distinguish between the effects of gradients and/or absolute concentration effects of NaCl and KCl. Uptake depends on the concentration of KCl on the inside, but not on a gradient in KCl. This points to a role for K+ as a regulator of uptake rate, but not of total uptake. The uptake of glutamate is not inhibited by a number of acids with similar chemical groups. Inhibition is, however, caused by D-glutamate. This indicates a specific transport site for glutamate. Parallel results are obtained for binding of glutamate to a Triton extract of the vesicle membrane. The variation in binding and uptake properties with the salt concentration is discussed with reference to transport kinetics.
authors.forename: N K
authors.initials: NK
authors.lastname: Birkeland
authors.forename: S K
authors.initials: SK
authors.lastname: Ratkje
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism; D001693:Biological Transport, Active / Q000187:drug effects; D005971:Glutamates / Q000378:metabolism*; D018698:Glutamic Acid; D006217:Halobacterium / Q000378:metabolism*; D007700:Kinetics; D010101:Oxygen Consumption / Q000187:drug effects; D012965:Sodium Chloride / Q000494:pharmacology; D013347:Subcellular Fractions / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D005971:Glutamates; D018698:Glutamic Acid; D012965:Sodium Chloride