The Signature Sequence Region of the Human Drug Transporter Organic Anion Transporting Polypeptide 1B1 Is Important for Protein Surface Expression

Figure 7

[³H]E3S uptake and luminometry results for OATP1B1-FLAG control and D251E, W254F, W258/259F, and N261A mutant constructs, transiently transfected into HEK293T cells. Uptake of 0.1 μM [³H]E3S at 37°C after 3 min was measured and pcDNA vector control uptake was subtracted. The OATP1B1-FLAG [³H]E3S uptake was 15.4 pmol/mg protein/3 min. Luminometry experiments were measured as RLU/mg protein and OATP1B1 (no epitope) negative control values were subtracted. Mutant values were normalized to those of the OATP1B1-FLAG and expressed as a percentage. Each bar is the mean ± SE of 3 experiments (luminometry = 3 dish replicates, uptake = 6-well replicates). *Statistical decrease () from the OATP1B1-FLAG was determined by a two-tailed one sample -test (Sigmaplot 11.0).