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| | ==Crystal Structure of Recombinant Human Complement Protein C8gamma== | | ==Crystal Structure of Recombinant Human Complement Protein C8gamma== |
| - | <StructureSection load='2ove' size='340' side='right' caption='[[2ove]], [[Resolution|resolution]] 2.00Å' scene=''> | + | <StructureSection load='2ove' size='340' side='right'caption='[[2ove]], [[Resolution|resolution]] 2.00Å' scene=''> |
| | == Structural highlights == | | == Structural highlights == |
| - | <table><tr><td colspan='2'>[[2ove]] is a 1 chain structure with sequence from [http://en.wikipedia.org/wiki/Human Human]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2OVE OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=2OVE FirstGlance]. <br> | + | <table><tr><td colspan='2'>[[2ove]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2OVE OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=2OVE FirstGlance]. <br> |
| - | </td></tr><tr id='related'><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat">[[1iw2|1iw2]], [[1lf7|1lf7]], [[2ova|2ova]], [[2ovd|2ovd]]</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]] 2Å</td></tr> |
| - | <tr id='gene'><td class="sblockLbl"><b>[[Gene|Gene:]]</b></td><td class="sblockDat">C8G ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=9606 HUMAN])</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=2ove FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2ove OCA], [https://pdbe.org/2ove PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=2ove RCSB], [https://www.ebi.ac.uk/pdbsum/2ove PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=2ove ProSAT]</span></td></tr> |
| - | <tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=2ove FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2ove OCA], [http://pdbe.org/2ove PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=2ove RCSB], [http://www.ebi.ac.uk/pdbsum/2ove PDBsum]</span></td></tr> | + | |
| | </table> | | </table> |
| | == Function == | | == Function == |
| - | [[http://www.uniprot.org/uniprot/CO8G_HUMAN CO8G_HUMAN]] C8 is a constituent of the membrane attack complex. C8 binds to the C5B-7 complex, forming the C5B-8 complex. C5-B8 binds C9 and acts as a catalyst in the polymerization of C9. The gamma subunit seems to be able to bind retinol. | + | [https://www.uniprot.org/uniprot/CO8G_HUMAN CO8G_HUMAN] C8 is a constituent of the membrane attack complex. C8 binds to the C5B-7 complex, forming the C5B-8 complex. C5-B8 binds C9 and acts as a catalyst in the polymerization of C9. The gamma subunit seems to be able to bind retinol. |
| | == Evolutionary Conservation == | | == Evolutionary Conservation == |
| | [[Image:Consurf_key_small.gif|200px|right]] | | [[Image:Consurf_key_small.gif|200px|right]] |
| | Check<jmol> | | Check<jmol> |
| | <jmolCheckbox> | | <jmolCheckbox> |
| - | <scriptWhenChecked>select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/ov/2ove_consurf.spt"</scriptWhenChecked> | + | <scriptWhenChecked>; select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/ov/2ove_consurf.spt"</scriptWhenChecked> |
| - | <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.spt</scriptWhenUnchecked> | + | <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview03.spt</scriptWhenUnchecked> |
| | <text>to colour the structure by Evolutionary Conservation</text> | | <text>to colour the structure by Evolutionary Conservation</text> |
| | </jmolCheckbox> | | </jmolCheckbox> |
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| | __TOC__ | | __TOC__ |
| | </StructureSection> | | </StructureSection> |
| - | [[Category: Human]] | + | [[Category: Homo sapiens]] |
| - | [[Category: Brannen, C]] | + | [[Category: Large Structures]] |
| - | [[Category: Chiswell, B]] | + | [[Category: Brannen C]] |
| - | [[Category: Lebioda, L]] | + | [[Category: Chiswell B]] |
| - | [[Category: Lovelace, L L]] | + | [[Category: Lebioda L]] |
| - | [[Category: Ortlund, E A]] | + | [[Category: Lovelace LL]] |
| - | [[Category: Sodetz, J M]] | + | [[Category: Ortlund EA]] |
| - | [[Category: Beta barrel]]
| + | [[Category: Sodetz JM]] |
| - | [[Category: Ligand binding protein]]
| + | |
| - | [[Category: Lipocalin]]
| + | |
| - | [[Category: Transport protein]]
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| Structural highlights
Function
CO8G_HUMAN C8 is a constituent of the membrane attack complex. C8 binds to the C5B-7 complex, forming the C5B-8 complex. C5-B8 binds C9 and acts as a catalyst in the polymerization of C9. The gamma subunit seems to be able to bind retinol.
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
Human C8 is one of five components of the cytolytic membrane attack complex of complement. It contains three subunits (C8alpha, C8beta, C8gamma) arranged as a disulfide-linked C8alpha-gamma heterodimer that is noncovalently associated with C8beta. C8gamma has the distinction of being the only lipocalin in the complement system. Lipocalins have a core beta-barrel structure forming a calyx with a binding site for a small hydrophobic ligand. A natural ligand for C8gamma has not been identified; however previous structural studies indicate C8gamma has a typical lipocalin fold that is suggestive of a ligand-binding capability. A distinctive feature of C8gamma is the division of its putative ligand binding pocket into a hydrophilic upper portion and a large hydrophobic lower cavity. Access to the latter is restricted by the close proximity of two tyrosine side chains (Y83 and Y131). In the present study, binding experiments were performed using lauric acid as a pseudoligand to investigate the potential accessibility of the lower cavity. The crystal structure of a C8gamma.laurate complex revealed that Y83 and Y131 can move to allow penetration of the hydrocarbon chain of laurate into the lower cavity. Introducing a Y83W mutation blocked access but had no effect on the ability of C8gamma to enhance C8 cytolytic activity. Together, these results indicate that the lower cavity in C8gamma could accommodate a ligand if such a ligand has a narrow hydrophobic moiety at one end. Entry of that moiety into the lower cavity would require movement of Y83 and Y131, which act as a gate at the cavity entrance.
Structural features of the ligand binding site on human complement protein C8gamma: a member of the lipocalin family.,Chiswell B, Lovelace LL, Brannen C, Ortlund EA, Lebioda L, Sodetz JM Biochim Biophys Acta. 2007 May;1774(5):637-44. Epub 2007 Mar 20. PMID:17452033[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Chiswell B, Lovelace LL, Brannen C, Ortlund EA, Lebioda L, Sodetz JM. Structural features of the ligand binding site on human complement protein C8gamma: a member of the lipocalin family. Biochim Biophys Acta. 2007 May;1774(5):637-44. Epub 2007 Mar 20. PMID:17452033 doi:http://dx.doi.org/10.1016/j.bbapap.2007.03.004
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