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  • Evidence for an UDP-glucuronic acid/phenol glucuronide antiport in rat liver microsomal vesicles.

Evidence for an UDP-glucuronic acid/phenol glucuronide antiport in rat liver microsomal vesicles.

The Biochemical journal (1996-04-01)
G Bánhegyi, L Braun, P Marcolongo, M Csala, R Fulceri, J Mandl, A Benedetti
摘要

The transport of glucuronides synthesized in the luminal compartment of the endoplasmic reticulum by UDP-glucuronosyltransferase isoenzymes was studied in rat liver microsomal vesicles. Microsomal vesicles were loaded with p-nitrophenol glucuronide (5 mM), phenolphthalein glucuronide or UDP-glucuronic acid, by a freeze-thawing method. In was shown that: (i) the loading procedure resulted in millimolar intravesicular concentrations of the different loading compounds; (ii) addition of UDP-glucuronic acid (5 mM) to the vesicles released both intravesicular glucuronides within 1 min; (iii) glucuronides stimulated the release of UDP-glucuronic acid from UDP acid-loaded microsomal vesicles; (iv) trans-stimulation of UDP-glucuronic acid entry by loading of microsomal vesicles with p-nitrophenol glucuronide, phenolphthalein glucuronide, UDP-glucuronic acid and UDP-N-acetyl-glucosamine almost completely abolished the latency of UDP-glucuronosyltransferase, although mannose 6-phosphatase latency remained unaltered; (v) the loading compounds by themselves did not stimulate UDP-glucuronosyltransferase activity. This study indicates that glucuronides synthesized in the lumen of endoplasmic reticulum can leave by an antiport, which concurrently transports USP-glucuronic acid into the lumen of the endoplasmic reticulum.

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Sigma-Aldrich
苯酚 β-D-葡萄糖醛酸, β-glucuronidase substrate
Sigma-Aldrich
苯酚 β-D-葡萄糖醛酸 钠盐, β-glucuronidase substrate