title: Potassium transport and the relationship between intracellular potassium concentration and amino acid uptake by cells of a marine pseudomonad.
abstract: Transport of K(+) by K(+)-depleted cells of marine pseudomonad B-16 (ATCC 19855) exhibited saturation kinetics. Rb(+) inhibited both K(+) transport and the K(+)-dependent transport of alpha-aminoisobutyric acid (AIB) into K(+)-depleted cells of the organism in proportion to the concentration of Rb(+) in the suspending medium. Inhibition of the K(+)-dependent uptake of AIB into K(+)-depleted cells by Rb(+) could be overcome by increasing the concentration of K(+) in the medium. When AIB and K(+) were added simultaneously to a suspension of K(+)-depleted cells, the uptake of K(+) occurred immediately and rapidly, whereas the accumulation of AIB occurred only after a lag. The initial uptake rate of AIB was directly proportional to the intracellular K(+) concentration. The intracellular concentration of K(+) and AIB at their steady-state levels increased to a maximum as the Na(+) concentration in the suspending medium was increased. At Na(+) concentrations between 0.2 and 0.3 M, the molar ratio of K(+) to AIB at their intracellular steady-state concentrations was constant at 1.6. At external Na(+) concentrations less than 0.2 M, the cells maintained a relatively higher K(+) intracellular steady-state level than AIB.
mesh_terms: D000596:Amino Acids / Q000378:metabolism*; D000613:Aminobutyrates / Q000031:analogs & derivatives / Q000378:metabolism; D001693:Biological Transport, Active; D002247:Carbon Isotopes; D003470:Culture Media; D007700:Kinetics; D008386:Marine Biology; D011188:Potassium / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011194:Potassium Isotopes; D011549:Pseudomonas / Q000166:cytology* / Q000254:growth & development / Q000378:metabolism; D011868:Radioisotopes; D012413:Rubidium / Q000494:pharmacology; D012964:Sodium / Q000494:pharmacology
chemical_list: D000596:Amino Acids; D000613:Aminobutyrates; D002247:Carbon Isotopes; D003470:Culture Media; D011194:Potassium Isotopes; D011868:Radioisotopes; D012964:Sodium; D012413:Rubidium; D011188:Potassium