Kinetic parameters of bovine Oatp1a2 and human OATP1A2 on uptake of estrone-3-sulafte and taurocholate
Uptake of E-3-S was measured at concentrations from 0.01(0.05 μM for human OATP1A2) to 50 μM and from 0.5 to 100 μM for taurocholate at a 1-minute interval. Transport kinetic values were calculated using the Eadie-Hofstee transformation. The results shown are means ± S.E.M. (n = 3).
| Species | Substrate | Km | Vmax |
|---|---|---|---|
| μM | pmol/mg protein/min | ||
| Bovine | Estrone-3-sulfate | 0.25 ± 0.08 | 24.5 ± 4.4 |
| 46.6 ± 18.5 | 375 ± 142 | ||
| Taurocholate | 40.2 ± 10.0 | 55.4 ± 8.4 | |
| Human | Estrone-3-sulfate | 16.1 ± 3.4 | 39.4 ± 7.8 |
| Taurocholate | 15.9 ± 6.0 | 24.1 ± 4.1 |
E-3-S, estrone-3-sulfate; Km, Michaelis constant; OATP, organic anion transporting polypeptide.