Table I.
Kinetic data for 13N-ammonium uptake by AtAMT1;1 and AtAMT2 expressed in yeast
| Transporter | External pH | Km | Vmaxa |
|---|---|---|---|
| μm | nmol NH4+ min−1 unit A600−1 | ||
| AtAMT1;1 | 5.0 | 16 ± 0.5 | 5.3 ± 1.8 |
| 6.1 | 22 ± 1.1 | 5.6 ± 1.2 | |
| 7.5 | 25 ± 2.5 | 2.7 ± 1.0 | |
| AtAMT2 | 5.0 | 23 ± 5.5 | 0.3 ± 0.2 |
| 6.1 | 21 ± 3 | 0.5 ± 0.3 | |
| 7.5 | 22 ± 1.3 | 1.9 ± 0.5 |
Values are derived from Figure 6B.
a
The background rate of ammonium uptake measured in the mutant strain YCW012 containing pYES3 was taken into account when calculating Vmax. Estimates of error represent 95% confidence intervals and were calculated from independent samples.