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Molecular identification and functional characterization of rat multidrug and toxin extrusion type transporter 1 as an organic cation/H+ antiporter in the kidney.

Authors: Ohta, KY  Inoue, K  Hayashi, Y  Yuasa, H 
Citation: Ohta KY, etal., Drug Metab Dispos. 2006 Nov;34(11):1868-74. Epub 2006 Aug 23.
Pubmed: (View Article at PubMed) PMID:16928787
DOI: Full-text: DOI:10.1124/dmd.106.010876

We have cloned and functionally characterized the rat ortholog of multidrug and toxin extrusion type transporter 1 (rMATE1). The mRNA of rMATE1 was strongly expressed in kidney and detectable in the various tissues such as brain, stomach, colon, lung, liver, spleen, skeletal muscle, and prostate. When stably expressed in HEK293 cells, rMATE1 could mediate the transport of tetraethylammonium (TEA) and cimetidine under the condition where the membrane potential was disrupted by a high concentration of potassium ion and intracellular pH was reduced by NH(4)Cl pretreatment. When extracellular pH was changed from 5.5 to 8.5, the transport of TEA by rMATE1 was greatest at pH 7.5. Kinetic analyses showed that the transports of TEA and cimetidine mediated by rMATE1 were both saturable with a K(m) of 260 +/- 10 and 3.01 +/- 0.21 muM, respectively. It was found that cimetidine is the most potent inhibitor of rMATE1, and many other organic cations, such as 1-methyl-4-phenylpyridinium, amiloride, imipramine, and quinidine, are also effective as inhibitors. Pretreatment of the cells expressing rMATE1 with p-chloromercuribenzene sulfonate significantly reduced TEA transport, but this effect was totally reversed by subsequent treatment with dithiothreitol. These results indicate that the functional nature of rMATE1 is consistent with that of the hypothetical organic cation/H(+) antiporter system in the brush-border membrane of the renal tubular epithelial cells. Accordingly, these results suggest that rMATE1 is an electroneutral and multispecific organic cation transporter energized by the trans-proton gradient, and plays a physiological role in renal secretion of organic cations, including clinically used cationic drugs.


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RGD Object Information
RGD ID: 2316962
Created: 2010-03-05
Species: All species
Last Modified: 2010-03-05
Status: ACTIVE


RGD is funded by grant HL64541 from the National Heart, Lung, and Blood Institute on behalf of the NIH.