FIGURE 7.

Na⁺-activation kinetics of hCNT3 and mutants. Na⁺-activation curves for oocytes producing E343Q (A), E343D (B), E343C (C), E519D (D), E519C (E), or wild-type hCNT3 (F) were measured in transport medium containing 0–100 mm NaCl at pH 8.5 with isomolality maintained by addition of ChCl. A radiolabeled uridine concentration of 20 μm was used. Values were corrected for basal nonmediated uptake in control water-injected oocytes and are means ± S.E. of 10–12 oocytes. Kinetic parameters calculated from the data are presented in Table 3.