View source for 1tlg


==STRUCTURE OF A TUNICATE C-TYPE LECTIN COMPLEXED WITH D-GALACTOSE==
<StructureSection load='1tlg' size='340' side='right'caption='[[1tlg]], [[Resolution|resolution]] 2.20&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[1tlg]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Polyandrocarpa_misakiensis Polyandrocarpa misakiensis]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1TLG OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1TLG FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 2.2&#8491;</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=GAL:BETA-D-GALACTOSE'>GAL</scene>, <scene name='pdbligand=ZN:ZINC+ION'>ZN</scene></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=1tlg FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1tlg OCA], [https://pdbe.org/1tlg PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1tlg RCSB], [https://www.ebi.ac.uk/pdbsum/1tlg PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1tlg ProSAT]</span></td></tr>
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== Function ==
[https://www.uniprot.org/uniprot/LECC_POLMI LECC_POLMI] Role in the defense system of the organism against microorganisms. This calcium-binding lectin binds galactose.
== Evolutionary Conservation ==
[[Image:Consurf_key_small.gif|200px|right]]
Check<jmol>
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    <scriptWhenChecked>; select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/tl/1tlg_consurf.spt"</scriptWhenChecked>
    <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview03.spt</scriptWhenUnchecked>
    <text>to colour the structure by Evolutionary Conservation</text>
  </jmolCheckbox>
</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=1tlg ConSurf].
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== Publication Abstract from PubMed ==
C-type lectins are calcium-dependent carbohydrate-recognising proteins. Isothermal titration calorimetry of the C-type Polyandrocarpa lectin (TC14) from the tunicate Polyandrocarpa misakiensis revealed the presence of a single calcium atom per monomer with a dissociation constant of 2.6 microM, and confirmed the specificity of TC14 for D -galactose and related monosaccharides. We have determined the 2.2 A X-ray crystal structure of Polyandrocarpa lectin complexed with D -galactose. Analytical ultracentrifugation revealed that TC14 behaves as a dimer in solution. This is reflected by the presence of two molecules in the asymmetric unit with the dimeric interface formed by antiparallel pairing of the two N-terminal beta-strands and hydrophobic interactions. TC14 adopts a typical C-type lectin fold with differences in structure from other C-type lectins mainly in the diverse loop regions and in the second alpha-helix, which is involved in the formation of the dimeric interface. The D -galactose is bound through coordination of the 3 and 4-hydroxyl oxygen atoms with a bound calcium atom. Additional hydrogen bonds are formed directly between serine, aspartate and glutamate side-chains of the protein and the sugar 3 and 4-hydroxyl groups. Comparison of the galactose binding by TC14 with the mannose binding by rat mannose-binding protein reveals how monosaccharide specificity is achieved in this lectin. A tryptophan side-chain close to the binding site and the distribution of hydrogen-bond acceptors and donors around the 3 and 4-hydroxyl groups of the sugar are essential determinants of specificity. These elements are, however, arranged in a very different way than in an engineered galactose-specific mutant of MBPA. Possible biological functions can more easily be understood from the fact that TC14 is a dimer under physiological conditions.

The structure of a tunicate C-type lectin from Polyandrocarpa misakiensis complexed with D -galactose.,Poget SF, Legge GB, Proctor MR, Butler PJ, Bycroft M, Williams RL J Mol Biol. 1999 Jul 23;290(4):867-79. PMID:10398588<ref>PMID:10398588</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Large Structures]]
[[Category: Polyandrocarpa misakiensis]]
[[Category: Bycroft M]]
[[Category: Legge GB]]
[[Category: Poget SF]]
[[Category: Williams RL]]