Figure 5.

Uptake of pyridoxine and thiamine by mSlc19a3-hA3-5AA in transiently transfected HEK293 cells. The mSlc19a3 mutant of mSlc19a3-hA3-5AA was prepared by introducing the five hSLC19A3-specific amino acid residues suggested to be involved in the pyridoxine transport function (Fig. 4) in place of their mSlc19a3 counterparts. All the transporters and mutants were tagged with EGFP at the N terminus. A, the specific uptake of [³H]pyridoxine (5 nM) was evaluated for 2 min at pH 5.5 and 37 °C. B, the specific uptake of [³H]thiamine (5 nM) was evaluated for 2 min at pH 7.4 and 37 °C. The uptake of pyridoxine and thiamine by hSLC19A3 as a control was 46.6 and 58.8 fmol/min/mg protein, respectively. Data are presented as means ± SD (n = 3). EGFP, enhanced GFP; HEK293, human embryonic kidney 293 cell line; hSLC19A3, human solute carrier SLC19A3; mSlc19a3, mouse Slc19a3; ND, not detected.