. Author manuscript; available in PMC: 2011 Sep 4.

Published in final edited form as: J Membr Biol. 2010 Sep 4;236(3):279–290. doi: 10.1007/s00232-010-9300-3

Table 2.

Kinetic parameters of wild-type OATP1B1 and extracelluar mutants

Substrate	Mutant	K_m (μM)	V_max (pmol/mg/min)
E17βG	WT	5.35 ± 0.54	228 ± 19.8
	R57A	30.5 ± 3.64 ^*	319 ± 50.6
	R57K	8.62 ± 0.33 ^*	152 ± 31.3
	K361A	14.5 ± 2.02 ^*	178 ± 36.0
	K361R	11.9 ± 2.57 ^*	224 ± 24.3
E3S	WT	0.55 ± 0.12	38.6 ± 5.81
	R57A	0.81 ± 0.03	30.2 ± 5.53
	R57K	0.96 ± 0.21	22.4 ± 3.64
	K361A	0.54 ± 0.07	11.34 ± 2.95 ^*
	K361R	1.83 ± 0.33 ^*	23.9 ± 5.90
BSP	WT	0.46 ± 0.04	52.2 ± 9.42
	R57A	0.69 ± 0.04 ^*	38.5 ± 4.69
	R57K	0.40 ± 0.04	38.3 ± 4.34
	K361A	0.97 ± 0.14 ^*	52.4 ± 17.6
	K361R	1.05 ± 0.15 ^*	51.7 ± 23.7

Kinetic parameters of wild type and mutated OATP1B1-mediated E17βG (estradiol-17β-glucuronide), E3S (estrone-3-sulfate) and BSP (bromosulfophthalein) uptake were measured under initial linear rate conditions, corrected for surface expression and presented as mean ± SE of 3 to 13 independent experiments. Uptake of E17βG (1 μM to 50 μM) and BSP (0.05 μM to 3 μM) was measured at 37°C for 1 minute; uptake of E3S (0.05 μM to 2 μM) was measured at 37°C for 30 seconds;

p < 0.05.