TABLE 2.

Determination of substrates and inhibitors of zebrafish Oatp1d1

Shown is a kinetic analysis of LY transport by HEK293/Oatp1d1-overexpressing cells in the absence of an interactor (control) and in the presence of an interactor (at a concentration equal to its K_i value shown in Table I). In all cases, the LY uptake followed Michaelis-Menten type kinetics, where a K_m decrease and no change in the transport rate (V_m) in the presence of interactor indicates competitive inhibition (designated S for substrates); K_m decrease and V_m decrease indicates non-competitive inhibition; and finally, no change in K_m and a V_m decrease indicates uncompetitive inhibition (inhibitors are designated with “I”). Kinetic parameters of LY uptake are given as apparent K_m (K_m(app)) (μm), apparent V_m (V_m(app)) (nmol of LY/mg of protein/min), and 95% confidence intervals for each. Uptake was measured after a 15-min incubation at 37 °C. Data are mean ± S.E. from triplicate determinations.

Interactor	Km(app) (LY)	c.i.	Vm(app) (LY)	c.i.	Interaction type
Control	59.3	31.4–87.2	50.7	43.2–58.1
Estrone 3-sulfate	147	128–167	54.9	50.9–58.9	S
Estradiol 17β-glucuronide	93.6	73.9–113	56.3	50.1–62.5	S
Estradiol	61.7	44.9–78.5	31.6	27.9–35.2	I
Testosterone	54.6	37.7–71.5	15.6	13.1–18.1	I
Dihydrotestosterone	42.4	21.8–63.1	24.0	18.8–29.1	I
DHEAS	129	81.9–175	59.4	48.6–70.1	S
Androstenedione	60.1	35.9–84.2	40.6	36.1–45.2	I
Progesterone	56.2	32.8–79.6	20.3	16.3–24.3	I
Cortisol	84.3	32.7–136	76.6	53.4–99.8	S
Corticosterone	32.0	23.8–40.3	41.3	36.4–46.1	I
Triiodothyronine	22.6	12.8–32.4	16.8	14.3–19.2	I
Cholate	39.7	18.9–60.5	25.1	19.7–30.4	I
Deoxycholate	29.2	2.74–55.7	16.3	9.91–22.6	I
Taurocholate	64.1	3.06–125	16.9	11.5–22.2	I
Taurochenodeoxycholate	39.8	26.5–53.2	18.0	15.7–20.2	I
Bilirubin	36.1	19.1–53.1	20.6	16.8–24.4	I