Saturation kinetics of multidrug and toxin extrusion (MATE)1- and MATE2-K-mediated uptake of [14C]metformin, [3H]thiamine, [3H]MPP+, [3H]E3S, and rhodamine 123

Uptake of [14C]metformin (10–10,000 μM, 1 min), [3H]thiamine (0.1–1000 μM, 1 min), [3H]MPP+ (0.1–1000 μM, 1 min), [3H]E3S (0.1–300 μM, 2 min),and rhodamine 123 (0.1–100 μM, 2 min) was determined at condition A (see Table 1). Kinetic parameters were estimated by nonlinear regression analysis and are given as mean ± S.D. from one experiment in case of [14C]metformin and [3H]MPP+ and from one representative experiment of at least two separate experiments in case of the other substrates.

SubstrateKm (μM)Vmax (pmol/min/mg protein)
Rhodamine 1230.793±0.39510.2±1.2372±411796±64
  • n.d., not determined.

  • a Kinetic parameters of [3H]E3S were not determined owing to its atypical saturation kinetics.