TABLE 1

Kinetic parameters (K_m, V_max) of estrone-3-sulfate uptake by OATP2B1-expressing Xenopus oocytes

Kinetic parameters were obtained from Fig. 4. Data are shown as means ± S.E.M. (n = 4). OATP2B1-mediated uptake of estrone-3-sulfate was determined by subtracting the uptake by water-injected oocytes from that by OATP2B1 cRNA-injected oocytes.

Condition of Administration	Affinity Sites	K_m	V_max	V_max/K_m
		μM	pmol/min/oocyte	μl/min/oocyte
Control (without 2% AJ)	High	0.550 ± 0.150	0.288 ± 0.067	0.524
Control (without 2% AJ)	Low	41.0 ± 10.3	3.30 ± 0.36	0.0805
Coincubation with 2% AJ	High	1.32 ± 0.25^*	0.429 ± 0.007^*	0.325
Coincubation with 2% AJ	Low	66.1 ± 13.9	2.99 ± 0.25	0.0452
Preincubation with 2% AJ	High	0.506 ± 0.109	0.132 ± 0.027^*	0.261
Preincubation with 2% AJ	Low	27.8 ± 3.7^*	2.43 ± 1.89	0.0874

↵* P < 0.05, significantly different from control (without 2% AJ).