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.
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.