文章基本信息

标题：Identification of Organic Cation Transporter in Rat Renal Brush-Border Membrane by Photoaffinity Labeling
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作者：Michio KIMURA ; Tomohiro NABEKURA ; Toshiya KATSURA 等
期刊名称：Biological and Pharmaceutical Bulletin
印刷版ISSN：0918-6158
电子版ISSN：1347-5215
出版年度：1995
卷号：18
期号：3
页码：388-395
DOI：10.1248/bpb.18.388
出版社：The Pharmaceutical Society of Japan
摘要：As an approach to identification of the organic cation transport system in brush-border membranes, we designed a photoaffinity probe, 1-cyano-2-(4-azido [3, 5-³H] benzoylethyl)-3-[2-[[(5-methyl-4-imidazolyl) methyl] thio] ethyl]-guanidine ([³H] AMC) based on the molecular structure of cimetidine, which is taken up by the organic cation transport system in brush-border membrane vesicles. The effect of nonradioactive 1-cyano-2-(4-azidobenzoylethyl)-3-[2-[[(5-methyl-4-imidazolyl) methyl] thio] ethyl] guanidine (AMC) on tetraethylammonium uptake was investigated in rat renal brush-border membrane vesicles. We examined the photolysis of AMC in which the azido group was converted to an active nitrene group using UV light at a wavelength of 254 nm and established a half-life of 7 s. This half-life duration did not significantly impair brush-border membrane vesicles during the exposure to light for photo-labeling. Photoaffinity labeling of brush-border membrane vesicles from the rat renal cortex with [³H] AMC resulted in the covalent incorporation of radioactivity into membrane polypeptides ; an apparent 36 kDa polypeptide was predominantly labeled. Photolabeling specificity was shown by a reduction in the labeling of the 36 kDa polypeptide in the presence of organic cations, cimetidine, tetraethylammonium and N-methylnicotinamide whereas the organic anion, furosemide, had no effect on labeling patterns. These data demonstrate that AMC, as well as organic cations, cimetidine, tetraethylammonium and N-methylnicotinamide, interact with a common 36 kDa membrane polypeptide, which may be the transport system or one of its brush-border membrane components.
关键词：organic cation transporter;rat renal brush-border membrane;photoaffinity labeling;tetraethylammonium;cimetidine