Figure 2.

Characterization of [¹⁴C]-labeled urea transport by AtTIP2;1. A, Uptake rates of [¹⁴C]urea in AtTIP2;1-expressing and in uninjected control oocytes from X. laevis. Uptake was determined from 100 μm [¹⁴C]-labeled urea at pH 5 to 8 after 20 min of incubation. Bars = means ± sd, n = 3, of one representative experiment, except for control oocytes at pH 5 and 8, where n = 7 from two experiments. B, Concentration-dependent uptake of [¹⁴C]urea in AtTIP2;1-expressing oocytes was not saturable and displayed a linear concentration dependency up to 30 mm urea. Standard choline solutions at pH 7 were used. Symbols represent means ± sd, n = 3.