FIGURE 2.
pH sensitivity and effect of DEPC on SVCT2-mediated ascorbic acid transport in transfected HEK-293 cells. A, effect of pH on ascorbic acid transport. B, effect of pH 6.0 (●) and 7.4 (○) on the apparent ascorbic acid transport Vmax and Km. C, effect of pH 6.0 (●) and 7.4 (○) on the Na+ cooperativity. D, concentration-response curve of the effect of DEPC on ascorbic acid transport. E, ascorbic acid apparent transport Vmax and Km in cells treated with (●) or without (○) 300 μm DEPC. F, Na+ cooperativity in cells treated with (●) or without (○) 300 μm DEPC. G, pH sensitivity in cells treated with (●) or without (dashed line) 300 μm DEPC. Transport data correspond to the means ± S.D. (error bars) of one experiment of two performed in triplicate. Ascorbic acid transport, DEPC modification, and pH effects in transfected cells were assayed as indicated under “Experimental Procedures.”