Figure 6.

Uptake of pyridoxine and thiamine by mSlc19a3 mutants in transiently transfected HEK293 cells: the effect of the introduction of hTMDs.A, schematic representation of mSlc19a3 mutants that have single or multiple hTMDs in place of their mTMD counterparts. All the transporters and mutants were tagged with EGFP at the N terminus. B, the specific uptake of [³H]pyridoxine (5 nM) was evaluated for 2 min at pH 5.5 and 37 °C. C, the specific uptake of [³H]thiamine (5 nM) was evaluated for 2 min at pH 7.4 and 37 °C. D, the uptake ratio was calculated by dividing pyridoxine uptake by thiamine uptake, using uptake values in percent of control. The uptake of pyridoxine and thiamine by hSLC19A3 as a control was 58.5 and 50.2 fmol/min/mg protein, respectively. Data are presented as means ± SD (n = 3). EGFP, enhanced GFP; HEK293, human embryonic kidney 293 cell line; hTMD, TMD in hSLC19A3; mSlc19a3, mouse Slc19a3; mTMD, TMD in mSlc19a3; ND, not detected; TMD, transmembrane domain.