TABLE 2

Parameters describing the kinetics of creatinine transport by OAT2, OCT2, MATE1, and MATE2K

Data are expressed as mean ± SD (n = 3). The kinetic parameters were determined as indicated in Materials and Methods.

Transporter	K_m	V_max	V_max/K_m	V_max Ratio^{^a}	Intrinsic Transport Clearance Ratio^{^b}
Transporter	µM	pmol/min/mg Total Protein	µL/min/mg Total Protein	% Relative to OAT2	% Relative to OAT2
OAT2	795 ± 138	24,987 ± 1,204	31.4	100	100
OCT2	18,771 ± 1,139	17,546 ± 739	0.93	64.7	2.7
MATE1	10,234 ± 339	1,058 ± 20	0.10	0.7	0.054
MATE2K	21,597 ± 27,066	2,948 ± 3,477	0.14	34.3	1.3

↵^a V_max ratios are calculated as the ratios of creatinine uptake into transporter-expressing HEK cells, which are normalized to the expression of individual transporter proteins.
↵^b Intrinsic transport clearance is determined by dividing the V_max value by the K_m value, which is normalized to the expression of individual transporter protein.