Characterization of the transport system for beta-lactam antibiotics and dipeptides in rat renal brush-border membrane vesicles by photoaffinity labeling |
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Authors: | W Kramer I Leipe E Petzoldt F Girbig |
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Institution: | Hoechst Aktiengesellschaft, Frankfurt am Main, F.R.G. |
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Abstract: | The uptake of the alpha-aminocephalosporin cephalexin into brush-border membrane vesicles from rat renal cortex was independent on an inward H+-gradient in contrast to the intestinal transport system. The transport system could be irreversibly inhibited by photoaffinity labeling. Two binding polypeptides for beta-lactam antibiotics and dipeptides with apparent molecular weights 130,000 and 95,000 were identified by photoaffinity labeling with 3H]benzylpenicillin and N-(4-azido3,5-3H]benzoyl) derivatives of cephalexin and glycyl-L-proline. The uptake of cephalexin and the labeling of the respective binding proteins was inhibited by beta-lactam antibiotics and dipeptides as with intestinal brush-border membranes. These data indicate that the transport systems for beta-lactam antibiotics and dipeptides in the brush-border membrane from rat kidney and small intestine are similar but not identical. |
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