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1iga

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(New page: 200px<br /> <applet load="1iga" size="450" color="white" frame="true" align="right" spinBox="true" caption="1iga" /> '''MODEL OF HUMAN IGA1 DETERMINED BY SOLUTION ...)
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[[Image:1iga.gif|left|200px]]<br />
 
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<applet load="1iga" size="450" color="white" frame="true" align="right" spinBox="true"
 
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caption="1iga" />
 
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'''MODEL OF HUMAN IGA1 DETERMINED BY SOLUTION SCATTERING CURVE-FITTING AND HOMOLOGY MODELLING'''<br />
 
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==Overview==
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==MODEL OF HUMAN IGA1 DETERMINED BY SOLUTION SCATTERING CURVE-FITTING AND HOMOLOGY MODELLING==
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Human immunoglobulin A (IgA) is an abundant antibody that mediates immune, protection at mucosal surfaces as well as in plasma. The IgA1 isotype, contains two four-domain Fab fragments and a four-domain Fc fragment, analogous to that in immunoglobulin G (IgG), linked by a glycosylated, hinge region made up of 23 amino acid residues from each of the heavy, chains. IgA1 also has two 18 residue tailpieces at the C terminus of each, heavy chain in the Fc fragment. X-ray scattering using H2O buffers and, neutron scattering using 100 % 2H2O buffers were performed on monomeric, IgA1 and a recombinant IgA1 that lacks the tailpiece (PTerm455). The radii, of gyration RG from Guinier analyses were similar at 6.11-6.20 nm for IgA1, and 5.84-6.16 nm for PTerm455, and their cross-sectional radii of gyration, RXS were also similar. The similarity of the RG and RXS values suggests, that the tailpiece of IgA1 is not extended outwards in solution. The IgA1, RG values are higher than those for IgG, and the distance distribution, function P(r) showed two distinct peaks, whereas a single peak was, observed for IgG. Both results show that the hinge of IgA1 results in an, extended Fab and Fc arrangement that is different from that in IgG., Automated curve-fit searches constrained by homology models for the Fab, and Fc fragments were used to model the experimental IgA1 scattering, curves. A translational search to optimise the relative arrangement of the, Fab and Fc fragments held in a fixed orientation resembling that in IgG, was not successful in fitting the scattering data. A new molecular, dynamics curve-fit search method generated IgA1 hinge structures to which, the Fab and Fc fragments could be connected in any orientation. A search, based on these identified a limited family of IgA1 structures that gave, good curve fits to the experimental data. These contained extended hinges, of length about 7 nm that positioned the Fab-to-Fab centre-to-centre, separation 17 nm apart while keeping the corresponding Fab-to-Fc, separation at 9 nm. The resulting extended T-shaped IgA1 structures are, distinct from IgG structures previously determined by scattering and, crystallography which have Fab-to-Fab and Fab-to-Fc centre-to-centre, separations of 7-9 nm and 6-8 nm, respectively. It was concluded that the, IgA1 hinge is structurally distinct from that in IgG, and this results in, a markedly different antibody structure that may account for a unique, immune role of monomeric IgA1 in plasma and mucosa.
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<StructureSection load='1iga' size='340' side='right'caption='[[1iga]]' scene=''>
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== Structural highlights ==
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<table><tr><td colspan='2'>[[1iga]] is a 4 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=1IGA OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1IGA 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 solution scattering</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=1iga FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1iga OCA], [https://pdbe.org/1iga PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1iga RCSB], [https://www.ebi.ac.uk/pdbsum/1iga PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1iga ProSAT]</span></td></tr>
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</table>
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== Disease ==
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[https://www.uniprot.org/uniprot/IGHA1_HUMAN IGHA1_HUMAN] Note=A chromosomal aberration involving IGHA1 is found in multiple myeloma (MM) cell lines. Translocation t(1;14)(q21;q32) that forms a FCRL4-IGHA1 fusion protein.
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== Function ==
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[https://www.uniprot.org/uniprot/IGHA1_HUMAN IGHA1_HUMAN] Ig alpha is the major immunoglobulin class in body secretions. It may serve both to defend against local infection and to prevent access of foreign antigens to the general immunologic system.
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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/ig/1iga_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=1iga 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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1IGA is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1IGA OCA].
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*[[Antibody 3D structures|Antibody 3D structures]]
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*[[3D structures of human antibody|3D structures of human antibody]]
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==Reference==
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__TOC__
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The Fab and Fc fragments of IgA1 exhibit a different arrangement from that in IgG: a study by X-ray and neutron solution scattering and homology modelling., Boehm MK, Woof JM, Kerr MA, Perkins SJ, J Mol Biol. 1999 Mar 12;286(5):1421-47. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=10064707 10064707]
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</StructureSection>
[[Category: Homo sapiens]]
[[Category: Homo sapiens]]
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[[Category: Protein complex]]
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[[Category: Large Structures]]
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[[Category: Boehm, M.K.]]
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[[Category: Boehm MK]]
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[[Category: Kerr, M.A.]]
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[[Category: Kerr MA]]
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[[Category: Perkins, S.J.]]
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[[Category: Perkins SJ]]
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[[Category: Woof, J.M.]]
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[[Category: Woof JM]]
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[[Category: iga1]]
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[[Category: immunoglobulin]]
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''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Mon Nov 12 17:29:36 2007''
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Current revision

MODEL OF HUMAN IGA1 DETERMINED BY SOLUTION SCATTERING CURVE-FITTING AND HOMOLOGY MODELLING

PDB ID 1iga

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