Figure 9

Effect of pH on the transport activity of hLAT1-WT or hLAT1-K204Q mutant. The purified proteins, WT (□) and K204Q (◊), were reconstituted in proteoliposomes prepared with 75 μg cholesterol/mg phospholipids as described in “Methods” and buffered with 20 mM Hepes Tris at the indicated pH. Transport was started by adding 5 μM [³H]-histidine to proteoliposomes containing 10 mM histidine. The transport was measured in 15 min according to the stop inhibitor method. Transport rate was expressed as nmol/mg in 15 min. The pH was equal in both the internal and external sides of proteoliposomes. Results are means ± SD of at least three independent experiments.