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| | <StructureSection load='1yro' size='340' side='right'caption='[[1yro]], [[Resolution|resolution]] 1.90Å' scene=''> | | <StructureSection load='1yro' size='340' side='right'caption='[[1yro]], [[Resolution|resolution]] 1.90Å' scene=''> |
| | == Structural highlights == | | == Structural highlights == |
| - | <table><tr><td colspan='2'>[[1yro]] is a 4 chain structure with sequence from [https://en.wikipedia.org/wiki/Bovin Bovin] and [https://en.wikipedia.org/wiki/Lk3_transgenic_mice Lk3 transgenic mice]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1YRO OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1YRO FirstGlance]. <br> | + | <table><tr><td colspan='2'>[[1yro]] is a 4 chain structure with sequence from [https://en.wikipedia.org/wiki/Bos_taurus Bos taurus] and [https://en.wikipedia.org/wiki/Mus_musculus Mus musculus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1YRO OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1YRO FirstGlance]. <br> |
| - | </td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=CA:CALCIUM+ION'>CA</scene>, <scene name='pdbligand=GDU:GALACTOSE-URIDINE-5-DIPHOSPHATE'>GDU</scene>, <scene name='pdbligand=MES:2-(N-MORPHOLINO)-ETHANESULFONIC+ACID'>MES</scene>, <scene name='pdbligand=MN:MANGANESE+(II)+ION'>MN</scene>, <scene name='pdbligand=PG4:TETRAETHYLENE+GLYCOL'>PG4</scene>, <scene name='pdbligand=UDP:URIDINE-5-DIPHOSPHATE'>UDP</scene></td></tr> | + | </td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 1.9Å</td></tr> |
| - | <tr id='related'><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat"><div style='overflow: auto; max-height: 3em;'>[[1nkh|1nkh]], [[1o0r|1o0r]]</div></td></tr>
| + | <tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=CA:CALCIUM+ION'>CA</scene>, <scene name='pdbligand=GDU:GALACTOSE-URIDINE-5-DIPHOSPHATE'>GDU</scene>, <scene name='pdbligand=MES:2-(N-MORPHOLINO)-ETHANESULFONIC+ACID'>MES</scene>, <scene name='pdbligand=MN:MANGANESE+(II)+ION'>MN</scene>, <scene name='pdbligand=PG4:TETRAETHYLENE+GLYCOL'>PG4</scene>, <scene name='pdbligand=UDP:URIDINE-5-DIPHOSPHATE'>UDP</scene></td></tr> |
| - | <tr id='gene'><td class="sblockLbl"><b>[[Gene|Gene:]]</b></td><td class="sblockDat">alpha-lactalbumin ([https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=10090 LK3 transgenic mice]), beta1,4-galactosyltransferase ([https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=9913 BOVIN])</td></tr>
| + | |
| | <tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=1yro FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1yro OCA], [https://pdbe.org/1yro PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1yro RCSB], [https://www.ebi.ac.uk/pdbsum/1yro PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1yro ProSAT]</span></td></tr> | | <tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=1yro FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1yro OCA], [https://pdbe.org/1yro PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1yro RCSB], [https://www.ebi.ac.uk/pdbsum/1yro PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1yro ProSAT]</span></td></tr> |
| | </table> | | </table> |
| | == Function == | | == Function == |
| - | [[https://www.uniprot.org/uniprot/LALBA_MOUSE LALBA_MOUSE]] Regulatory subunit of lactose synthase, changes the substrate specificity of galactosyltransferase in the mammary gland making glucose a good acceptor substrate for this enzyme. This enables LS to synthesize lactose, the major carbohydrate component of milk. In other tissues, galactosyltransferase transfers galactose onto the N-acetylglucosamine of the oligosaccharide chains in glycoproteins. [[https://www.uniprot.org/uniprot/B4GT1_BOVIN B4GT1_BOVIN]] The Golgi complex form catalyzes the production of lactose in the lactating mammary gland and could also be responsible for the synthesis of complex-type N-linked oligosaccharides in many glycoproteins as well as the carbohydrate moieties of glycolipids. The cell surface form functions as a recognition molecule during a variety of cell to cell and cell to matrix interactions, as those occurring during development and egg fertilization, by binding to specific oligosaccharide ligands on opposing cells or in the extracellular matrix.
| + | [https://www.uniprot.org/uniprot/LALBA_MOUSE LALBA_MOUSE] Regulatory subunit of lactose synthase, changes the substrate specificity of galactosyltransferase in the mammary gland making glucose a good acceptor substrate for this enzyme. This enables LS to synthesize lactose, the major carbohydrate component of milk. In other tissues, galactosyltransferase transfers galactose onto the N-acetylglucosamine of the oligosaccharide chains in glycoproteins. |
| | == Evolutionary Conservation == | | == Evolutionary Conservation == |
| | [[Image:Consurf_key_small.gif|200px|right]] | | [[Image:Consurf_key_small.gif|200px|right]] |
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| | __TOC__ | | __TOC__ |
| | </StructureSection> | | </StructureSection> |
| - | [[Category: Bovin]] | + | [[Category: Bos taurus]] |
| | [[Category: Large Structures]] | | [[Category: Large Structures]] |
| - | [[Category: Lk3 transgenic mice]] | + | [[Category: Mus musculus]] |
| - | [[Category: Boeggeman, E]] | + | [[Category: Boeggeman E]] |
| - | [[Category: Qasba, P K]] | + | [[Category: Qasba PK]] |
| - | [[Category: Ramakrishnan, B]] | + | [[Category: Ramakrishnan B]] |
| - | [[Category: Arg228lys mutation]]
| + | |
| - | [[Category: Transferase activator-transferase complex]]
| + | |
| - | [[Category: Udp-gal complex]]
| + | |
| Structural highlights
1yro is a 4 chain structure with sequence from Bos taurus and Mus musculus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
| | Method: | X-ray diffraction, Resolution 1.9Å |
| Ligands: | , , , , , |
| Resources: | FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT |
Function
LALBA_MOUSE Regulatory subunit of lactose synthase, changes the substrate specificity of galactosyltransferase in the mammary gland making glucose a good acceptor substrate for this enzyme. This enables LS to synthesize lactose, the major carbohydrate component of milk. In other tissues, galactosyltransferase transfers galactose onto the N-acetylglucosamine of the oligosaccharide chains in glycoproteins.
Evolutionary Conservation
Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.
Publication Abstract from PubMed
Beta-1,4-galactosyltransferase I (beta4Gal-T1) normally transfers Gal from UDP-Gal to GlcNAc in the presence of Mn(2+) ion (Gal-T activity) and also transfers Glc from UDP-Glc to GlcNAc (Glc-T activity), albeit at only 0.3% efficiency. In addition, alpha-lactalbumin (LA) enhances this Glc-T activity more than 25 times. Comparison of the crystal structures of UDP-Gal- and UDP-Glc-bound beta4Gal-T1 reveals that the O4 hydroxyl group in both Gal and Glc moieties forms a hydrogen bond with the side chain carboxylate group of Glu317. The orientation of the O4 hydroxyl of glucose causes a steric hindrance to the side chain carboxylate group of Glu317, accounting for the enzyme's low Glc-T activity. In this study, we show that mutation of Arg228, a residue in the vicinity of Glu317, to lysine (R228K-Gal-T1) results in a 15-fold higher Glc-T activity, which is further enhanced by LA to nearly 25% of the Gal-T activity of the wild type. The kinetic parameters indicate that the main effect of the mutation of Arg228 to lysine is on the k(cat) of Glc-T, which increases 3-4-fold, both in the absence and in the presence of LA; simultaneously, the k(cat) for the Gal-T reaction is reduced 30-fold. The crystal structure of R228K-Gal-T1 complexed with LA, UDP-Gal, and Mn(2+) determined at 1.9 A resolution shows that the Asp318 side chain exhibits a minor alternate conformation, compared to that in the wild type. This alternate conformation now causes a steric hindrance to the O4 hydroxyl group of the Gal moiety of UDP-Gal, probably causing the dissociation of UDP-Gal and the reduced k(cat) of the Gal-T reaction.
Mutation of arginine 228 to lysine enhances the glucosyltransferase activity of bovine beta-1,4-galactosyltransferase I.,Ramakrishnan B, Boeggeman E, Qasba PK Biochemistry. 2005 Mar 8;44(9):3202-10. PMID:15736931[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
- ↑ Ramakrishnan B, Boeggeman E, Qasba PK. Mutation of arginine 228 to lysine enhances the glucosyltransferase activity of bovine beta-1,4-galactosyltransferase I. Biochemistry. 2005 Mar 8;44(9):3202-10. PMID:15736931 doi:10.1021/bi0479454
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