TABLE 1.

Kinetics of [³H]MPP⁺ uptake in 293T cells following transfection with expression plasmids^a

Transfected plasmid(s)	Km (μM)	Vmax (pmol/min/mg of protein)b
OCT2 + vector	30.43 ± 4.11	101.40 ± 3.73
OCT2 + RS1	29.76 ± 7.50	68.15 ± 4.90*
OCT2 + IRIP	32.88 ± 7.18	72.67 ± 4.92*
OCT2 + RS1 + IRIP	36.54 ± 6.21	77.60 ± 4.35*

^aCells were transfected with plasmids expressing corresponding proteins and assayed for [³H]MPP⁺ transport as described in Materials and Methods. K_m and V_max values for [³H]MPP⁺ uptake are the mean ± standard error of the mean of three independent experiments, each performed in triplicate. K_m and V_max values were obtained by nonlinear least-squares regression analysis.

^b*, P < 0.05, two-tailed Student's t test.