CATION TRANSPORT IN ESCHERICHIA COLI. IV. KINETICS OF NET K UPTAKE.
The resuspension of K-poor, Na-rich stationary phase E. coli in fresh medium at pH 7.0 results in a rapid uptake of K and extrusion of Na by the cells. In all experiments net K uptake exceeded net Na extrusion. An investigation of the uptake of glucose, PO(4), and Mg and the secretion of H by these cells indicates that the excess K uptake is not balanced by the simultaneous uptake of anions but must be accompanied by the extrusion of cations from the cell. The kinetics of net K uptake are consistent with the existence of two parallel influx processes. The first is rapid, of brief duration, and accounts for approximately 60 per cent of the total net K uptake. This process is a function of the extracellular K concentration, is inhibited in acid media, and appears to be a 1 for 1 exchange of extracellular K for intracellular H. The second influx process has a half-time of approximately 12 minutes, and is not affected by acid media. This process is a function of the intracellular Na concentration, is dependent upon the presence of K in the medium, and may be ascribed to a 1 for 1 exchange of extracellular K for intracellular Na.
D000838:Anions; D050260:Carbohydrate Metabolism; D002412:Cations; D004926:Escherichia coli; D005947:Glucose; D006859:Hydrogen; D007477:Ions; D007700:Kinetics; D008660:Metabolism; D011188:Potassium; D012106:Research; D012964:Sodium
D000838:Anions; D002412:Cations; D007477:Ions; D006859:Hydrogen; D012964:Sodium; D005947:Glucose; D011188:Potassium
CARBOHYDRATE METABOLISM; ESCHERICHIA COLI; EXPERIMENTAL LAB STUDY; GLUCOSE; HYDROGEN; METABOLISM; POTASSIUM; SODIUM