Sodium and Potassium Requirements for Active Transport of Glutamate by Escherichia coli K-12
AUTOR(ES)
Halpern, Y. S.
RESUMO
Active transport of glutamate by Escherichia coli K-12 requires both Na+ and K+ ions. Increasing the concentration of Na+ in the medium results in a decrease in the Km of the uptake system for glutamate; the capacity is not affected. Glutamate uptake by untreated cells is not stimulated by K+. K+-depleted cells show a greatly reduced capacity for glutamate uptake. Preincubation of such cells in the presence of K+ fully restores their capacity for glutamate uptake when Na+ ions are also present in the uptake medium. Addition of either K+ or Na+ alone restores glutamate uptake to only about 20% of its maximum capacity in the presence of both cations. Changes in K+ concentration affect the capacity for glutamate uptake but have no effect on the Km of the glutamate transport system. Ouabain does not inhibit the (Na+-K+)-stimulated glutamate uptake by intact cells or spheroplasts of E. coli K-12.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=251739Documentos Relacionados
- Potassium Transport Loci in Escherichia coli K-12
- Active Transport of Biotin in Escherichia coli K-12
- Potassium-Dependant Mutants of Escherichia coli K-12
- Genetic and Physiological Analysis of Glutamate Decarboxylase in Escherichia coli K-12
- Transport Systems for Alanine, Serine, and Glycine in Escherichia coli K-12
