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1nmm

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[[Image:1nmm.jpg|left|200px]]<br /><applet load="1nmm" size="350" color="white" frame="true" align="right" spinBox="true"
 
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caption="1nmm, resolution 2.00&Aring;" />
 
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'''beta-1,4-galactosyltransferase mutant Cys342Thr complex with alpha-lactalbumin and GlcNAc'''<br />
 
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==Overview==
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==beta-1,4-galactosyltransferase mutant Cys342Thr complex with alpha-lactalbumin and GlcNAc==
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beta-1,4-Galactosyltransferase 1 (Gal-T1) transfers galactose (Gal) from UDP-Gal to N-acetylglucosamine (GlcNAc), which constitutes its normal galactosyltransferase (Gal-T) activity. In the presence of alpha-lactalbumin (LA), it transfers Gal to Glc, which is its lactose synthase (LS) activity. It also transfers glucose (Glc) from UDP-Glc to GlcNAc, constituting the glucosyltransferase (Glc-T) activity, albeit at an efficiency of only 0.3-0.4% of Gal-T activity. In the present study, we show that LA increases this activity almost 30-fold. It also enhances the Glc-T activity toward various N-acyl substituted glucosamine acceptors. Steady state kinetic studies of Glc-T reaction show that the K(m) for the donor and acceptor substrates are high in the absence of LA. In the presence of LA, the K(m) for the acceptor substrate is reduced 30-fold, whereas for UDP-Glc it is reduced only 5-fold. In order to understand this property, we have determined the crystal structures of the Gal-T1.LA complex with UDP-Glc x Mn(2+) and with N-butanoyl-glucosamine (N-butanoyl-GlcN), a preferred sugar acceptor in the Glc-T activity. The crystal structures reveal that although the binding of UDP-Glc is quite similar to UDP-Gal, there are few significant differences observed in the hydrogen bonding interactions between UDP-Glc and Gal-T1. Based on the present kinetic and crystal structural studies, a possible explanation for the role of LA in the Glc-T activity has been proposed.
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<StructureSection load='1nmm' size='340' side='right'caption='[[1nmm]], [[Resolution|resolution]] 2.00&Aring;' scene=''>
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== Structural highlights ==
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<table><tr><td colspan='2'>[[1nmm]] 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=1jn8 1jn8]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1NMM OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1NMM 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&#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=NAG:N-ACETYL-D-GLUCOSAMINE'>NAG</scene>, <scene name='pdbligand=PG4:TETRAETHYLENE+GLYCOL'>PG4</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=1nmm FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1nmm OCA], [https://pdbe.org/1nmm PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1nmm RCSB], [https://www.ebi.ac.uk/pdbsum/1nmm PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1nmm 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/nm/1nmm_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=1nmm 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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1NMM 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 <scene name='pdbligand=NAG:'>NAG</scene>, <scene name='pdbligand=CA:'>CA</scene> and <scene name='pdbligand=PG4:'>PG4</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. This structure supersedes the now removed PDB entry 1JN8. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1NMM 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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alpha-Lactalbumin (LA) stimulates milk beta-1,4-galactosyltransferase I (beta 4Gal-T1) to transfer glucose from UDP-glucose to N-acetylglucosamine. Crystal structure of beta 4Gal-T1 x LA complex with UDP-Glc., Ramakrishnan B, Shah PS, Qasba PK, J Biol Chem. 2001 Oct 5;276(40):37665-71. Epub 2001 Aug 2. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=11485999 11485999]
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</StructureSection>
[[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: Shah PS]]
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[[Category: Shah, P S.]]
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[[Category: CA]]
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[[Category: NAG]]
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[[Category: PG4]]
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[[Category: 4-galactosyltransferase]]
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[[Category: alpha-lactalbumin complex]]
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[[Category: beta1]]
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[[Category: cys342thr mutation]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 14:07:45 2008''
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Current revision

beta-1,4-galactosyltransferase mutant Cys342Thr complex with alpha-lactalbumin and GlcNAc

PDB ID 1nmm

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