Enzymes
| UniProtKB help_outline | 4 proteins |
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- Name help_outline UDP-α-D-xylose Identifier CHEBI:57632 Charge -2 Formula C14H20N2O16P2 InChIKeyhelp_outline DQQDLYVHOTZLOR-OCIMBMBZSA-L SMILEShelp_outline O[C@@H]1CO[C@H](OP([O-])(=O)OP([O-])(=O)OC[C@H]2O[C@H]([C@H](O)[C@@H]2O)n2ccc(=O)[nH]c2=O)[C@H](O)[C@H]1O 2D coordinates Mol file for the small molecule Search links Involved in 25 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline UDP-α-D-glucuronate Identifier CHEBI:58052 Charge -3 Formula C15H19N2O18P2 InChIKeyhelp_outline HDYANYHVCAPMJV-LXQIFKJMSA-K SMILEShelp_outline O[C@@H]1[C@@H](COP([O-])(=O)OP([O-])(=O)O[C@H]2O[C@@H]([C@@H](O)[C@H](O)[C@H]2O)C([O-])=O)O[C@H]([C@@H]1O)n1ccc(=O)[nH]c1=O 2D coordinates Mol file for the small molecule Search links Involved in 107 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
Cross-references
| RHEA:74831 | RHEA:74832 | RHEA:74833 | RHEA:74834 | |
|---|---|---|---|---|
| Reaction direction help_outline | undefined | left-to-right | right-to-left | bidirectional |
| UniProtKB help_outline |
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Publications
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Carrier-mediated transport of uridine diphosphoglucuronic acid across the endoplasmic reticulum membrane is a prerequisite for UDP-glucuronosyltransferase activity in rat liver.
Bossuyt X., Blanckaert N.
UDP-glucuronosyltransferases (EC 2.4.1.17) is an isoenzyme family located primarily in the hepatic endoplasmic reticulum (ER) that displays latency of activity both in vitro and in vivo, as assessed respectively in microsomes and in isolated liver. The postulated luminal location of the active sit ... >> More
UDP-glucuronosyltransferases (EC 2.4.1.17) is an isoenzyme family located primarily in the hepatic endoplasmic reticulum (ER) that displays latency of activity both in vitro and in vivo, as assessed respectively in microsomes and in isolated liver. The postulated luminal location of the active site of UDP-glucuronosyltransferases (UGTs) creates a permeability barrier to aglycone and UDP-GlcA access to the enzyme and implies a requirement for the transport of substrates across the ER membrane. The present study shows that the recently demonstrated carrier-mediated transport of UDP-GlcA across the ER membrane is required and rate-limiting for glucuronidation in sealed microsomal vesicles as well as in the intact ER of permeabilized hepatocytes. We found that in both microsomes and permeabilized hepatocytes a gradual inhibition by N-ethylmaleimide (NEM) of UDP-GlcA transport into the ER produced a correspondingly increasing inhibition of 4-methylumbelliferone glucuronidation. That NEM selectively inhibited the UDP-GlcA transporter, without affecting intrinsic UGT activity, was demonstrated by showing that NEM had no effect on glucuronidation in microsomes or hepatocytes with permeabilized ER membrane. Additional evidence that UDP-GlcA transport is rate-limiting for glucuronidation in sealed microsomal vesicles as well as in the intact ER of permeabilized hepatocytes was obtained by showing that gradual selective trans-stimulation of UDP-GlcA transport by UDP-GlcNAc, UDP-Xyl or UDP-Glc in each case produced correspondingly enhanced glucuronidation. Such stimulation of transport and glucuronidation was inhibited completely by NEM, which selectively inhibited UDP-GlcA transport. << Less
Biochem J 323:645-648(1997) [PubMed] [EuropePMC]
This publication is cited by 1 other entry.
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Differential regulation of UDP-GlcUA transport in endoplasmic reticulum and in Golgi membranes.
Bossuyt X., Blanckaert N.
<h4>Background</h4>In the endoplasmic reticulum (ER), the stimulation of UDP-glucuronosyltransferase (UGT) by UDP-GlcNAc is based on the interaction of transport across the ER membrane of UDP-GlcUA with UDP-GlcNAc. Intramicrosomal UDP-GlcNAc stimulates influx of UDP-GlcUA and thereby enhances deli ... >> More
<h4>Background</h4>In the endoplasmic reticulum (ER), the stimulation of UDP-glucuronosyltransferase (UGT) by UDP-GlcNAc is based on the interaction of transport across the ER membrane of UDP-GlcUA with UDP-GlcNAc. Intramicrosomal UDP-GlcNAc stimulates influx of UDP-GlcUA and thereby enhances delivery of UDP-GlcUA to the catalytic center of UGT in the ER lumen.<h4>Aim</h4>The aim of this study is to investigate whether the interactions between nucleotide sugars for transport across the ER membrane also occur in the Golgi apparatus, and thereby affect UGT activity in Golgi membranes.<h4>Results</h4>We found that Golgi membrane preparations display UGT activity which, unlike in ER membranes, is not stimulated by UDP-GlcNAc. Efflux of intravesicular UDP-GlcNAc and UDP-Xyl marginally enhanced uptake of UDP-GlcUA in Golgi vesicles; such trans-stimulation was much more pronounced in the ER. Efflux of intravesicular UDP-GlcNAc was strongly trans-stimulated by cytosolic UDP-GlcUA in ER-derived vesicles but less so in Golgi-derived vesicles.<h4>Conclusion</h4>The interaction between transport of UDP-GlcUA and transport of UDP-GlcNAc or UDP-Xyl is different in Golgi vesicles compared with ER vesicles. This finding is consistent with the different effects of UDP-GlcNAc on glucuronidation in Golgi and ER. << Less
J Hepatol 34:210-214(2001) [PubMed] [EuropePMC]
This publication is cited by 1 other entry.