Involvement of Histidine Residue His382 in pH Regulation of MCT4 Activity
Fig 7
Transport of lactate via MCT4-mutant.
(A) Oocytes injected with MCT4-WT cRNA, MCT4-H382A cRNA, or water were incubated with 0.1 mM lactate (0.1 μCi/ml) for 10 min. (B) Sensitivities against 5 mM zinc of lactate transport activities via MCT4 with a histidine residue mutant. Uptake of 0.1 mM lactate (0.1 μCi/ml) was measured at pH 7.5 for 10 min. (C) Wild-type and histidine mutant MCT4 cRNA-injected oocytes were incubated for 10 min with/without 2.5 mM DEPC in a buffer of pH 7.5 at 25°C. Uptake of 0.1 mM lactate (0.1 μCi/ml) was measured for 10 min at pH 5.5. (D) pH regulation of lactate uptake via wild-type and mutant MCT4. Uptake of 0.1 mM lactate was measured for 10 min at the indicated pH by oocytes expressing proteins of interest. Values are presented as percentages of uptake measured at pH 5.5. All data are presented as means±S.E. of three experiments.