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1oqm

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(New page: 200px<br /><applet load="1oqm" size="450" color="white" frame="true" align="right" spinBox="true" caption="1oqm, resolution 2.10&Aring;" /> '''A 1:1 complex betwee...)
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[[Image:1oqm.gif|left|200px]]<br /><applet load="1oqm" size="450" color="white" frame="true" align="right" spinBox="true"
 
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caption="1oqm, resolution 2.10&Aring;" />
 
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'''A 1:1 complex between alpha-lactalbumin and beta1,4-galactosyltransferase in the presence of UDP-N-acetyl-galactosamine'''<br />
 
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==Overview==
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==A 1:1 complex between alpha-lactalbumin and beta1,4-galactosyltransferase in the presence of UDP-N-acetyl-galactosamine==
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beta1,4-Galactosyltransferase I (Gal-T1) normally transfers Gal from, UDP-Gal to GlcNAc in the presence of Mn(2+) ion. In the presence of, alpha-lactalbumin (LA), the Gal acceptor specificity is altered from, GlcNAc to Glc. Gal-T1 also transfers GalNAc from UDP-GalNAc to GlcNAc, but, with only approximately 0.1% of Gal-T activity. To understand this low, GalNAc-transferase activity, we have carried out the crystal structure, analysis of the Gal-T1.LA complex with UDP-GalNAc at 2.1-A resolution. The, crystal structure reveals that the UDP-GalNAc binding to Gal-T1 is similar, to the binding of UDP-Gal to Gal-T1, except for an additional hydrogen, bond formed between the N-acetyl group of GalNAc moiety with the Tyr-289, side chain hydroxyl group. Elimination of this additional hydrogen bond by, mutating Tyr-289 residue to Leu, Ile, or Asn enhances the, GalNAc-transferase activity. Although all three mutants exhibit enhanced, GalNAc-transferase activity, the mutant Y289L exhibits GalNAc-transferase, activity that is nearly 100% of its Gal-T activity, even while completely, retaining its Gal-T activity. The steady state kinetic analyses on the, Leu-289 mutant indicate that the K(m) for GlcNAc has increased compared to, the wild type. On the other hand, the catalytic constant (k(cat)) in the, Gal-T reaction is comparable with the wild type, whereas it is 3-5-fold, higher in the GalNAc-T reaction. Interestingly, in the presence of LA, these mutants also transfer GalNAc to Glc instead of to GlcNAc. The, present study demonstrates that, in the Gal-T family, the Tyr-289/Phe-289, residue largely determines the sugar donor specificity.
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<StructureSection load='1oqm' size='340' side='right'caption='[[1oqm]], [[Resolution|resolution]] 2.10&Aring;' scene=''>
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== Structural highlights ==
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<table><tr><td colspan='2'>[[1oqm]] 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]. This structure supersedes the now removed PDB entry [http://oca.weizmann.ac.il/oca-bin/send-pdb?obs=1&id=1l7w 1l7w]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1OQM OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1OQM FirstGlance]. <br>
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</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 2.1&#8491;</td></tr>
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<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=MN:MANGANESE+(II)+ION'>MN</scene>, <scene name='pdbligand=PG4:TETRAETHYLENE+GLYCOL'>PG4</scene>, <scene name='pdbligand=UD2:URIDINE-DIPHOSPHATE-N-ACETYLGALACTOSAMINE'>UD2</scene></td></tr>
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<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=1oqm FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1oqm OCA], [https://pdbe.org/1oqm PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1oqm RCSB], [https://www.ebi.ac.uk/pdbsum/1oqm PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1oqm ProSAT]</span></td></tr>
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</table>
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== Function ==
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[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.
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== Evolutionary Conservation ==
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[[Image:Consurf_key_small.gif|200px|right]]
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Check<jmol>
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<jmolCheckbox>
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<scriptWhenChecked>; select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/oq/1oqm_consurf.spt"</scriptWhenChecked>
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<scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.spt</scriptWhenUnchecked>
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<text>to colour the structure by Evolutionary Conservation</text>
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</jmolCheckbox>
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</jmol>, as determined by [http://consurfdb.tau.ac.il/ ConSurfDB]. You may read the [[Conservation%2C_Evolutionary|explanation]] of the method and the full data available from [http://bental.tau.ac.il/new_ConSurfDB/main_output.php?pdb_ID=1oqm ConSurf].
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<div style="clear:both"></div>
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==About this Structure==
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==See Also==
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1OQM is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Bos_taurus Bos taurus] and [http://en.wikipedia.org/wiki/Mus_musculus Mus musculus] with CA, MN, UD2 and PG4 as [http://en.wikipedia.org/wiki/ligands ligands]. This structure superseeds the now removed PDB entry 1L7W. Active as [http://en.wikipedia.org/wiki/Beta-N-acetylglucosaminylglycopeptide_beta-1,4-galactosyltransferase Beta-N-acetylglucosaminylglycopeptide beta-1,4-galactosyltransferase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.4.1.38 2.4.1.38] Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1OQM OCA].
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*[[Alpha-lactalbumin 3D structures|Alpha-lactalbumin 3D structures]]
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*[[Glycosyltransferase 3D structures|Glycosyltransferase 3D structures]]
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==Reference==
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__TOC__
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Structure-based design of beta 1,4-galactosyltransferase I (beta 4Gal-T1) with equally efficient N-acetylgalactosaminyltransferase activity: point mutation broadens beta 4Gal-T1 donor specificity., Ramakrishnan B, Qasba PK, J Biol Chem. 2002 Jun 7;277(23):20833-9. Epub 2002 Mar 26. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=11916963 11916963]
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</StructureSection>
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[[Category: Beta-N-acetylglucosaminylglycopeptide beta-1,4-galactosyltransferase]]
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[[Category: Bos taurus]]
[[Category: Bos taurus]]
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[[Category: Large Structures]]
[[Category: Mus musculus]]
[[Category: Mus musculus]]
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[[Category: Protein complex]]
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[[Category: Qasba PK]]
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[[Category: Qasba, P.K.]]
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[[Category: Ramakrishnan B]]
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[[Category: Ramakrishnan, B.]]
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[[Category: CA]]
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[[Category: MN]]
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[[Category: PG4]]
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[[Category: UD2]]
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[[Category: 4-galactosyltransferase]]
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[[Category: alpha-lactalbumin]]
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[[Category: beta1]]
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[[Category: udp-galnac]]
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''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Tue Nov 20 23:06:31 2007''
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Current revision

A 1:1 complex between alpha-lactalbumin and beta1,4-galactosyltransferase in the presence of UDP-N-acetyl-galactosamine

PDB ID 1oqm

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