Enzymes
| UniProtKB help_outline | 7 proteins |
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- Name help_outline a β-D-glucosyl-(1↔1ʼ)-N-acylsphing-4-enine Identifier CHEBI:22801 Charge 0 Formula C25H46NO8R SMILEShelp_outline CCCCCCCCCCCCC\C=C\[C@@H](O)[C@H](CO[C@@H]1O[C@H](CO)[C@@H](O)[C@H](O)[C@H]1O)NC([*])=O 2D coordinates Mol file for the small molecule Search links Involved in 20 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline UDP-α-D-galactose Identifier CHEBI:66914 Charge -2 Formula C15H22N2O17P2 InChIKeyhelp_outline HSCJRCZFDFQWRP-ABVWGUQPSA-L SMILEShelp_outline OC[C@H]1O[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](O)[C@H]1O 2D coordinates Mol file for the small molecule Search links Involved in 105 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline a β-D-Gal-(1→4)-β-D-Glc-(1↔1)-Cer(d18:1(4E)) Identifier CHEBI:17950 Charge 0 Formula C31H56NO13R SMILEShelp_outline CCCCCCCCCCCCC\C=C\[C@@H](O)[C@H](CO[C@@H]1O[C@H](CO)[C@@H](O[C@@H]2O[C@H](CO)[C@H](O)[C@H](O)[C@H]2O)[C@H](O)[C@H]1O)NC([*])=O 2D coordinates Mol file for the small molecule Search links Involved in 12 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline H+ Identifier CHEBI:15378 Charge 1 Formula H InChIKeyhelp_outline GPRLSGONYQIRFK-UHFFFAOYSA-N SMILEShelp_outline [H+] 2D coordinates Mol file for the small molecule Search links Involved in 9,431 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline UDP Identifier CHEBI:58223 Charge -3 Formula C9H11N2O12P2 InChIKeyhelp_outline XCCTYIAWTASOJW-XVFCMESISA-K SMILEShelp_outline O[C@@H]1[C@@H](COP([O-])(=O)OP([O-])([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 576 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
Cross-references
| RHEA:31495 | RHEA:31496 | RHEA:31497 | RHEA:31498 | |
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| Reaction direction help_outline | undefined | left-to-right | right-to-left | bidirectional |
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More general form(s) of this reaction
Publications
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Purification of uridine diphosphate-galactose:glucosyl ceramide, beta 1-4 galactosyltransferase from human kidney.
Chatterjee S., Ghosh N., Khurana S.
A galactosyltransferase that transfers galactose from UDP-galactose to glucosylceramide was purified 440-fold to apparent homogeneity from normal human kidney "buffy coat" preparation employing detergent extraction, ultrafiltration, and Sepharose Q column chromatography. On reducing and nonreducin ... >> More
A galactosyltransferase that transfers galactose from UDP-galactose to glucosylceramide was purified 440-fold to apparent homogeneity from normal human kidney "buffy coat" preparation employing detergent extraction, ultrafiltration, and Sepharose Q column chromatography. On reducing and nonreducing gels, the enzyme resolved into two bands with apparent molecular weights on the order of 60,000 and 58,000, respectively. The activity of the enzyme was also associated with these two bands following separation on polyacrylamide gels. Analytical isoelectric focusing revealed that the pI of this enzyme is approximately 4.55. Product characterization and substrate specificity studies employing chromatography, enzymatic digestion with various glycosidases, and use of a variety of glycosphingolipid substrates revealed that the major product synthesized by this enzyme was Cer1-1 beta Glc4-1Gal, and Cer1-1 beta Glc was the preferred substrate. Digestion of the 60- and 58-kDa proteins with Staphylococcus aureus (V-8) protease revealed at least six peptides having identical electrophoretic migration. This finding suggests that the two proteins may be related to each other. Western immunoblot assays revealed that the antibody against UDP-galactose:GlcCer, beta 1-4 galactosyltransferase (GalT-2) but not galactosyltransferase UDP-Gal:N-acetyl-D-glucosaminyl-glycopeptide 4-beta-D-galactosyltransferase (EC 2.4.1.38) (B-GT) immunoprecipitated (recognized) the kidney GalT-2. In contrast, antibody against B-GT did not immunoprecipitate GalT-2. Thus our data indicate that GalT-2 and B-GT are two distinct enzymes. The availability of the enzyme GalT-2 and corresponding antibody will allow functional studies in the near future. << Less
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UDPgalactose:glucosylceramide beta 1->4-galactosyltransferase activity in human proximal tubular cells from normal and familial hypercholesterolemic homozygotes.
Chatterjee S., Castiglione E.
The activity of a galactosyltransferase (GalT-2) that catalyzes the transfer of galactose from uridinediphosphogalactose to glucosylceramide in cultured normal human proximal tubular (PT) cells was characterized with respect to substrate saturation and metal ion requirements. Using a membrane-boun ... >> More
The activity of a galactosyltransferase (GalT-2) that catalyzes the transfer of galactose from uridinediphosphogalactose to glucosylceramide in cultured normal human proximal tubular (PT) cells was characterized with respect to substrate saturation and metal ion requirements. Using a membrane-bound enzyme source, optimum activity was obtained in the presence of 1.0 mM Mn2+/Mg2+ (1:1) and a detergent mixture, Triton X-100/Cutscum (1:2, v/v), 0.1 mg/ml. The apparent Km values for glucosylceramide and UDP[14C]galactose were 3 microM and 0.5 microM, respectively. The Vmax values for glucosylceramide and UDP[U-14C]galactose were 0.12 nmol/mg protein per 2 h and 173 nmol/mg protein per 2 h, respectively. The purified 14C-labelled product comigrated with authentic lactosylceramide (LacCer) on TLC and HPLC analysis. The presence of a terminal beta-[14C]galactosyl group in the enzymatic product was proved by its cleavage (79%) by beta-galactosidase. Following the development of optimal assay conditions in normal PT cells, GalT-2 activity was next measured in urinary PT cells from homozygous familial hypercholesterolemic (FH) patients previously shown to accumulate large amounts of lactosylceramide. Urinary PT cells from familial hypercholesterolemic homozygous patients contained 35% higher GalT-2 activity as compared to control cells. We speculate that elevated GalT-2 activity may contribute to the storage of LacCer in FH-PT cells. << Less
Biochim. Biophys. Acta 923:136-142(1987) [PubMed] [EuropePMC]
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Lactosylceramide synthases encoded by B4galt5 and 6 genes are pivotal for neuronal generation and myelin formation in mice.
Yoshihara T., Satake H., Nishie T., Okino N., Hatta T., Otani H., Naruse C., Suzuki H., Sugihara K., Kamimura E., Tokuda N., Furukawa K., Fururkawa K., Ito M., Asano M.
It is uncertain which β4-galactosyltransferase (β4GalT; gene name, B4galt), β4GalT-5 and/or β4GalT-6, is responsible for the production of lactosylceramide (LacCer) synthase, which functions in the initial step of ganglioside biosynthesis. Here, we generated conditional B4galt5 knockout (B4galt5 c ... >> More
It is uncertain which β4-galactosyltransferase (β4GalT; gene name, B4galt), β4GalT-5 and/or β4GalT-6, is responsible for the production of lactosylceramide (LacCer) synthase, which functions in the initial step of ganglioside biosynthesis. Here, we generated conditional B4galt5 knockout (B4galt5 cKO) mice, using Nestin-Cre mice, and crossed these with B4galt6 KO mice to generate B4galt5 and 6 double KO (DKO) mice in the central nervous system (CNS). LacCer synthase activity and major brain gangliosides were completely absent in brain homogenates from the DKO mice, although LacCer synthase activity was about half its normal level in B4galt5 cKO mice and B4galt6 KO mice. The DKO mice were born normally but they showed growth retardation and motor deficits at 2 weeks and died by 4 weeks of age. Histological analyses showed that myelin-associated proteins were rarely found localized in axons in the cerebral cortex, and axonal and myelin formation were remarkably impaired in the spinal cords of the DKO mice. Neuronal cells, differentiated from neurospheres that were prepared from the DKO mice, showed impairments in neurite outgrowth and branch formation, which can be explained by the fact that neurospheres from DKO mice could weakly interact with laminin due to lack of gangliosides, such as GM1a. Furthermore, the neurons were immature and perineuronal nets (PNNs) were poorly formed in DKO cerebral cortices. Our results indicate that LacCer synthase is encoded by B4galt5 and 6 genes in the CNS, and that gangliosides are indispensable for neuronal maturation, PNN formation, and axonal and myelin formation. << Less
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Purification, cDNA cloning, and expression of UDP-Gal: glucosylceramide beta-1,4-galactosyltransferase from rat brain.
Nomura T., Takizawa M., Aoki J., Arai H., Inoue K., Wakisaka E., Yoshizuka N., Imokawa G., Dohmae N., Takio K., Hattori M., Matsuo N.
Lactosylceramide synthase is an enzyme that catalyzes the transfer of galactose from UDP-Gal to glucosylceramide, and thus participates in the biosynthesis of most glycosphingolipids in mammals. We purified this enzyme over 61,000-fold to near homogeneity with a 29. 7% yield from rat brain membran ... >> More
Lactosylceramide synthase is an enzyme that catalyzes the transfer of galactose from UDP-Gal to glucosylceramide, and thus participates in the biosynthesis of most glycosphingolipids in mammals. We purified this enzyme over 61,000-fold to near homogeneity with a 29. 7% yield from rat brain membrane fractions. The isolation procedure included solubilization with Triton X-100, affinity chromatography on wheat germ agglutinin-agarose and UDP-hexanolamine-agarose, and hydroxylapatite column chromatography, followed by ion exchange chromatography. The final preparation migrated as a broad band with an apparent molecular mass of 61 kDa on SDS-polyacrylamide gel electrophoresis. This apparent molecular mass was reduced to 51 kDa by N-glycanase digestion, suggesting that the enzyme has a glycoprotein nature. The enzyme required Mn2+ for its activity, and glucosylceramide was its preferred substrate. The cDNA for the enzyme was cloned from a rat brain cDNA library. The cDNA insert encoded a polypeptide of 382 amino acid residues, with a molecular weight of 44,776. The polypeptide contained eight putative glycosylation sites and a 20-amino acid residue transmembrane domain at its N terminus. Amino acid sequence homology analysis revealed that this enzyme shared 39% homology with mouse beta-1, 4-galactosyltransferase (EC 2.4.1.38), which catalyzes the transfer of Gal to beta-1,4-GlcNAc in glycoproteins. << Less
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Involvement of murine beta-1,4-galactosyltransferase V in lactosylceramide biosynthesis.
Kumagai T., Sato T., Natsuka S., Kobayashi Y., Zhou D., Shinkai T., Hayakawa S., Furukawa K.
Human β-1,4-galactosyltransferase (β-1,4-GalT) V was shown to be involved in the biosynthesis of N-glycans, O-glycans and lactosylceramide (Lac-Cer) by in vitro studies. To determine its substrate specificity, enzymatic activity and its products were analyzed using mouse embryonic fibroblast (MEF) ... >> More
Human β-1,4-galactosyltransferase (β-1,4-GalT) V was shown to be involved in the biosynthesis of N-glycans, O-glycans and lactosylceramide (Lac-Cer) by in vitro studies. To determine its substrate specificity, enzymatic activity and its products were analyzed using mouse embryonic fibroblast (MEF) cells from β-1,4-GalT V (B4galt5)-mutant mice. Analysis of expression levels of the β-1,4-GalT I-VI genes revealed that the expression of the β-1,4-GalT V gene in B4galt5 ( +/-) - and B4galt5 ( -/-) -derived MEF cells are a half and null when compared to that of B4galt5 ( +/+ )-derived MEF cells without altering the expression levels of other β-1,4-GalT genes. These MEF cells showed no apparent difference in their growth. When β-1,4-GalT activities were determined towards GlcNAcβ-S-pNP, no significant difference in its specific activity was obtained among B4galt5 ( +/+ )-, B4galt5 ( +/- ) - and B4galt5 ( -/-) -derived MEF cells. No significant differences were obtained in structures and amounts of N-glycans and lectin bindings to membrane glycoproteins among B4galt5 ( +/+ )-, B4galt5 ( +/- ) - and B4galt5 ( -/-) -derived MEF cells. However, when cell homogenates were incubated with glucosylceramide in the presence of UDP-[(3)H]Gal, Lac-Cer synthase activity in B4galt5 ( +/- ) - and B4galt5 ( -/-) -derived MEF cells decreased to 41% and 11% of that of B4galt5 ( +/+ )-derived MEF cells. Consistent with this, amounts of Lac-Cer and its derivative GM3 in B4galt5 ( -/-) -derived MEF cells decreased remarkably when compared with those of B4galt5 ( +/+ )-derived MEF cells. These results indicate that murine β-1,4-GalT V is involved in Lac-Cer biosynthesis. << Less
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cDNA cloning and expression of human lactosylceramide synthase.
Takizawa M., Nomura T., Wakisaka E., Yoshizuka N., Aoki J., Arai H., Inoue K., Hattori M., Matsuo N.
Lactosylceramide synthase is an enzyme that catalyzes the transfer of galactose from UDP-Gal to glucosylceramide, and thus participates in the biosynthesis of most glycolipids in mammals. We have isolated and sequenced the cDNA clone encoding human lactosylceramide synthase. The deduced amino acid ... >> More
Lactosylceramide synthase is an enzyme that catalyzes the transfer of galactose from UDP-Gal to glucosylceramide, and thus participates in the biosynthesis of most glycolipids in mammals. We have isolated and sequenced the cDNA clone encoding human lactosylceramide synthase. The deduced amino acid sequence of the human lactosylceramide synthase showed 94.2% identity with rat lactosylceramide synthase. Northern blotting analysis revealed that lactosylceramide synthase mRNA was expressed in various tissues, with the highest level in brain and adrenal gland. << Less
Biochim. Biophys. Acta 1438:301-304(1999) [PubMed] [EuropePMC]