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PURPOSE To assess the functional characteristics of human organic anion transporter B (OATP-B) in comparison with those of the known, liver-specific OATP-C. METHODS OATP-B or -C was expressed in HEK293 cells or Xenopus oocytes, and uptakes of estradiol-17beta-glucuronide and estrone-3-sulfate were measured using radiolabeled compounds. RESULTS OATP-C(More)
We identified three novel transporters structurally belonging to the organic anion transporting polypeptide (OATP) family in humans. Since previously known rat oatp1 to 3 do not necessarily correspond to the human OATPs in terms of either tissue distribution or function, here we designate the newly identified human OATPs as OATP-B, -D and -E, and we rename(More)
The pH-sensitive activity of human organic anion transporting polypeptide OATP-B, which is expressed at the apical membrane of human small intestinal epithelial cells, was functionally characterized. When initial uptake of estrone-3-sulfate, a typical substrate of OATP, was studied kinetically, we observed an increase in V(max) with decrease of pH from 7.4(More)
Carnitine is essential for beta-oxidation of fatty acids, and a defect of cell membrane transport of carnitine leads to fatal systemic carnitine deficiency. We have already shown that a defect of the organic cation/carnitine transporter OCTN2 is a primary cause of systemic carnitine deficiency. In the present study, we further isolated and characterized new(More)
Primary carnitine deficiency, because of a defect of the tissue plasma membrane carnitine transporters, causes critical symptoms. However, the transporter has not been molecularly identified. In this study, we screened a human kidney cDNA library and assembled a cDNA-encoding OCTN2 as a homologue of the organic cation transporter OCTN1, and then we examined(More)
Primary systemic carnitine deficiency (SCD; OMIM 212140) is an autosomal recessive disorder characterized by progressive cardiomyopathy, skeletal myopathy, hypoglycaemia and hyperammonaemia. SCD has also been linked to sudden infant death syndrome. Membrane-physiological studies have suggested a defect of the carnitine transport system in the plasma(More)
cDNA for a novel proton/organic cation transporter, OCTN1, was cloned from human fetal liver and its transport activity was investigated. OCTN1 encodes a 551-amino acid protein with 11 transmembrane domains and one nucleotide binding site motif. It is strongly expressed in kidney, trachea, bone marrow and fetal liver and in several human cancer cell lines,(More)
Transport of L-[3H]carnitine and acetyl-L-[3H]carnitine at the blood-brain barrier (BBB) was examined by using in vivo and in vitro models. In vivo brain uptake of acetyl-L-[3H]carnitine, determined by a rat brain perfusion technique, was decreased in the presence of unlabeled acetyl-L-carnitine and in the absence of sodium ions. Similar transport(More)
Troglitazone is a thiazolidinedione insulin sensitizer drug that is metabolized mainly to a sulfate conjugate (M-1) in humans. It was reported to cause hepatotoxicity, although the cause has not been fully clarified. The objective of this study was to identify whether organic anion transporting polypeptide (OATP) transporters expressed at the basolateral(More)