Table 1. Kinetic parameters ± S.E.M. of MCT1/basigin fusion variants (nD: Not determined).
| Construct | Uptake rate* nmol mg−1 min–1 | Uptake capacity† nmol mg−1 & (mM) | Km (mM) | vmax (nmol min−1 mg−1) | Membr. loc. rel. intensity |
|---|---|---|---|---|---|
| MCT1 | 0.049 ± 0.005 | 0.11 ± 0.01 (0.39 ± 0.05) | 2.8 ± 0.2 | 0.187 ± 0.009 | 1.00 ± 0.13 |
| + BSGΔIg | 0.037 ± 0.004 | 0.11 ± 0.01 (0.39 ± 0.03) | 2.4 ± 0.7 | 0.125 ± 0.037 | 0.59 ± 0.07 |
| + BSG Ig-I | 0.105 ± 0.008 | 0.50 ± 0.01 (1.77 ± 0.04) | 3.9 ± 0.1 | 0.419 ± 0.024 | 1.66 ± 0.11 |
| + BSG Ig-I C23S | 0.012 ± 0.001 | 0.12 ± 0.02 (0.44 ± 0.07) | nD | nD | nD |
| + BSG Ig-I C82S | 0.007 ± 0.002 | 0.05 ± 0.01 (0.18 ± 0.05) | nD | nD | nD |
| + BSG Ig-I/C2 | 0.098 ± 0.013 | 0.59 ± 0.01 (2.11 ± 0.02) | 6.8 ± 3.1 | 0.431 ± 0.175 | 0.79 ± 0.06 |
| + BSG var2 | 0.021 ± 0.002 | 0.51 ± 0.06 (1.82 ± 0.20) | 1.2 ± 0.2 | 0.041 ± 0.006 | 0.58 ± 0.07 |
| + BSG Glu→Gln (114,118,120,168,172) | 0.069 ± 0.006 | 0.25 ± 0.01 (0.89 ± 0.04) | nD | nD | nD |
| + BSG Lys/Arg→Ala (108,111,127/201,203) | 0.005 ± 0.001 | 0.11 ± 0.01 (0.39 ± 0.03) | nD | nD | nD |
| + BSG Lys108,111Ala | 0.133 ± 0.031 | 0.47 ± 0.07 (1.70 ± 0.24) | nD | nD | nD |
| + BSG Arg201,203Ala | 0.013 ± 0.002 | 0.25 ± 0.01 (0.91 ± 0.01) | nD | nD | nD |
* dependent on the number of active transporters in the plasma membrane (1 mM external l-lactate, pH 6.8).
† independent of the number of active transporters (1 mM external l-lactate, pH 6.8).