FIGURE 4.

Characterization of molecular properties of OAT10 as a urate transporter. Transiently OAT10-expressing 293A cells were subjected to a cell-based urate transport assay, 48 h after transfection. Acidic pH (A), external Cl⁻ (B), time (C), and concentration (D) dependent urate transport activities of OAT10 in Ringer solution (pH 6.4) containing 10 μM [8–¹⁴C]-urate (unless otherwise indicated). To prepare Cl⁻-free Ringer solution, all chloride salts in Ringer solution were replaced with each corresponding gluconate salt (B). OAT10-mediated urate transport [lower panels: (C,D)] was calculated by subtracting the urate transport activity in mock cells from that in OAT10-expressing cells [upper panels: (C,D)]. Data are expressed as the mean ± SD; n = 3 (A), 4 (B–D). ^†† p < 0.01; NS, not significantly different between groups (two-sided t-test). With the estimated Michaelis-Menten constant (K _m) and maximal velocity (V _max), the values of 95% confidence interval were in parentheses.