Table 2. Functional analysis of wild-type (Wt) hOAT1 and K59R.

For PAH uptake, transport of [¹⁴C]PAH (20 μM, 10 min) in COS-7 cells expressing Wt hOAT1 or K59R was measured. Uptake activity was expressed as a percentage of the uptake measured in Wt. For efflux studies, cells expressing Wt hOAT1 or K59R were preloaded with [¹⁴C]PAH (100 μM) for 1 h, followed by an exposure to PBS (control group) or PBS containing α-oxoglutarate (experimental group). The amount of intracellular [¹⁴C]PAH in the experimental group was expressed as a percentage of that in the control group. For inhibition by probenecid, transport of PAH in COS-7 cells expressing Wt hOAT1 or K59R was measured in the presence (experimental group) and absence (control group) of 0.5 mM probenecid. Uptake activity remaining in the experimental group was expressed as a percentage of that measured in the control group. The results represent data from three experiments, with triplicate measurements for each transporter construct. The uptake value from pcDNA vector-transfected cell (mock cells) was subtracted from all other uptake values.

OAT	Uptake of PAH	Efflux of [14C]PAH	Inhibition of PAH uptake by probenecid
Wt hOAT1	100.0±15.6	72.8±4.5	10.9±1.7
K59R	112.4±8.0	72.4±3.5	12.7±1.3