title: A novel human organic anion transporter NPT4 mediates the transport of ochratoxin A.
abstract: In the present study, we investigated the transport of nephrotoxic mycotoxin ochratoxin A (OTxA) by a novel human organic anion transporter hNPT4 using the Xenopus oocyte expression system. hNPT4 mediated time- and concentration-dependent uptake of OTxA (K(m): 802.8 µM) in a pH- and voltage-sensitive manner. Cis-inhibition experiments suggest that the substrate selectivity of hNPT4 is similar to that of hOAT4. The fact that the K(m) of OTxA for the efflux transporter hNPT4 was much higher than those for the uptake transporters hOAT1 and hOAT3 may favor the accumulation of OTxA in the tubular cell and lead to nephrotoxicity.
authors.affiliation: Department of Pharmacology and Toxicology, Kyorin University School of Medicine, Tokyo, Japan.
authors.forename: Promsuk
authors.initials: P
authors.lastname: Jutabha
authors.forename: Naohiko
authors.initials: N
authors.lastname: Anzai
authors.forename: Keitaro
authors.initials: K
authors.lastname: Hayashi
authors.forename: Mariko
authors.initials: M
authors.lastname: Domae
authors.forename: Kohsuke
authors.initials: K
authors.lastname: Uchida
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Endou
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Sakurai
mesh_terms: D000818:Animals; D001692:Biological Transport / Q000502:physiology; D006801:Humans; D009793:Ochratoxins / Q000378:metabolism*; D009865:Oocytes; D029362:Organic Anion Transporters, Sodium-Independent / Q000378:metabolism*; D050609:Sodium-Phosphate Cotransporter Proteins, Type I / Q000378:metabolism*; D014981:Xenopus
chemical_list: D009793:Ochratoxins; D029362:Organic Anion Transporters, Sodium-Independent; C493550:SLC17A3 protein, human; D050609:Sodium-Phosphate Cotransporter Proteins, Type I; C025589:ochratoxin A