Molecular cloning and functional expression of a multispecific
organic anion transporter from human kidney.
Hosoyamada, Makoto, Takashi Sekine, Yoshikatsu Kanai, and Hitoshi
Endou.
Department of Pharmacology and Toxicology, Kyorin University School
of Medicine, 6-20-2 Shinkawa, Mitaka, Tokyo 181, Japan
APStracts 5:0177F, 1998.
Recently, we isolated the multispecific organic anion transporter
(OAT1) from the rat kidney, which plays important roles in the renal
elimination of endogenous and exogenous organic anions including
clinically important drugs. In the present study, we cloned and
characterized human OAT1. Two cDNA clones, hOAT1-1 cDNA and hOAT1-2
cDNA were isolated from a human kidney cDNA library, whose amino acid
sequences were 86.0% and 87.8% identical to that of rat OAT1,
respectively. When expressed in Xenopus laevis oocytes, hOAT1
mediated sodium-independent uptake of para-aminohippurate (PAH) (Km =
9.3+/-1.0 _M). hOAT1-mediated PAH uptake was inhibited by bulky
inorganic anions, various xenobiotics and endogenous substances,
including benzylpenicillin, furosemide, indomethacin, probenecid,
phenol red, urate and a-ketoglutarate. Northern blot analysis
revealed that hOAT1 mRNA is strongly expressed in human kidney;
transcripts of different sizes are expressed in skeletal muscle,
brain and placenta. Immunohistochemical analysis using rabbit IgG
antibody against the carboxyl-terminal 14 peptides of hOAT1 revealed
that hOAT1 is expressed at the basolateral membrane of the proximal
tubule. hOAT1 gene was located on human chromosome 11q13.1 by FISH
analysis. These results indicate that hOAT1 is a multispecific
organic anion transporter on the basolateral membrane of the proximal
tubule in human kidney.
Received 23 April 1998; accepted in final form 28 September 1998.
APS Manuscript Number F91-8.
Article publication pending Am. J. Physiol. (Renal Physiology).
ISSN 1080-4757 Copyright 1998 The American Physiological Society.
Published in APStracts on 20 October 1998