Table 1.
Comparison of kinetic and thermodynamic properties of hSGLT2 and hSGLT1 at 37°C
| hSGLT2 | hSGLT1 | |
|---|---|---|
| K0.5d-glucose, mM | 4.9 ± 0.6 | 1.8 ± 0.2 |
| K0.5αMDG, mM | 6.0 ± 0.9 | 3.8 ± 0.2 |
| K0.5d-galactose, mM | ≥100 | 6.1 ± 0.4 |
| K0.5Na, mM | 25 ± 10 | 73 ± 19 |
| Hill coefficient (nh) | 0.9 ± 0.2 | 1.5 ± 0.1 |
| Na+:glucose coupling (n) | 1:1 | 2:1 |
| Kiphlorizin, nM | 11 ± 0.9 | 140 ± 15 |
| t1/2,Offphlorizin, s | 24 ± 3 | 4 ± 0.5 |
| kOffphlorizin, s−1 | 0.030 ± 0.003 | 0.19 ± 0.02 |
| kOnphlorizin, M/s | 2.7 × 106 | 1.4 × 106 |
Values are means ± SE for n ≥ 3 cells at −60 mV. Rate constant for phlorizin binding (kOnphlorizin) is calculated from the Ki and the phlorizin release rate constant (kOffphlorizin). hSGLT, human Na+/d-glucose cotransporter; αMDG, [14C]-α-methyl-d-glucopyranoside; K0.5, substrate concentration at half-maximal current; t1/2,Off, half-time of recovery of glucose current after removal of phlorizin.