TABLE 1

Kinetic parameters of estrone-3-sulfate transport by wild-type OATP2B1 and TM1 mutants

Uptake of ES was measured at concentrations ranging from 0.05 to 50 μM for wild-type OATP2B1 and mutants at 37°C at a 1-minute interval and normalized with cell surface expression of the transporter. Transporter kinetic parameters were determined with nonlinear regression of Michaelis-Menten equation incorporated in GraphPad Prism 5. The results shown are means ± S.D. (n = 3).

	K_m	V_max
	μM	pmol/mg protein/min
OATP2B1	6.40 ± 0.30	351 ± 1
F51Y	7.30 ± 1.70	365 ± 6
V52A	5.28 ± 1.54	71.4 ± 3.4^*
H55A	6.75 ± 1.17	86.5 ± 2.0^*
L58A	18.4 ± 2.6^*	314 ± 29
Q59A	6.27 ± 0.65	27.9 ± 3.1^*
A61V	24.9 ± 4.2^*	213 ± 20^*
Q62A	7.36 ± 1.01^*	134 ± 1^*
S66A	10.1 ± 0.7^*	167 ± 4^*
L69A	7.20 ± 1.30	73.3 ± 4.8^*

↵* Values significantly different (P < 0.05) from that of wild-type OATP2B1.