Kinetics of DA uptake, MPP+ uptake, and CFT binding by hDAT, Chi hb3 (I152V), and Chi hb3 (I152A) expressed transiently in COS 7 cells
| Substrates | DAT | Vmax | Km |
|---|---|---|---|
| normalized | μM | ||
| hDAT | 1.00 ± 0.110 | 2.23 ± 0.725 | |
| DA | Chi hb3 (I152V) | 0.96 ± 0.059 | 4.45 ± 0.634 |
| Chi hb3 (I152A) | 0.54 ± 0.1201-a | 7.21 ± 1.790 | |
| hDAT | 1.00 ± 0.050 | 1.189 ± 0.219 | |
| MPP+ | Chi hb3 (I152V) | 0.86 ± 0.058 | 1.139 ± 0.235 |
| Chi hb3 (I152A) | 0.31 ± 0.0301-a | 2.489 ± 0.690 | |
| hDAT | 1.00 ± 0.50 | 0.0170 ± 0.04 | |
| CFT | Chi hb3 (I152V) | 1.23 ± 0.42 | 0.0223 ± 0.03 |
| Chi hb3 (I152A) | 0.60 ± 0.541-a | 0.0433 ± 0.05 |
Km and Vmax values for uptake or binding are the mean ± S.E. of six experiments. Saturated DA uptake of hDAT averaged 1.33 pmol/105 cells/min, 1.29 pmol/105 cells/min for Chi hb3 (I152V), and 0.72 pmol/105 cells/min for Chi hb3 (I152A). Vmaxvalues for MPP+ uptake averaged 3.17 pmol/105cells/min, by hDAT-transfected cells, 2.74 pmol/105 cells/min and 1.00 pmol/105 cells/min each by Chi hb3 (I152V) or Chi hb3 (I152A)-transfected cells. Estimated Vmax values for CFT binding of hDAT was 0.006 pmol/105 cells/min, 0.007 pmol/105 cells/min for Chi hb3 (I152V), and 0.004 pmol/105 cells/min by Chi hb3 (I152A)-transfected cells.
↵1-a Significantly different from hDAT and chi hb3 (I152V) (P < .01, Tukey post hoc analysis of two-way ANOVA).