View source for 3qnz


==Orthorhombic form of IgG1 Fab fragment (in complex with antigenic tubulin peptide) sharing same Fv as IgA==
<StructureSection load='3qnz' size='340' side='right'caption='[[3qnz]], [[Resolution|resolution]] 2.20&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[3qnz]] is a 3 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=3QNZ OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=3QNZ 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=GOL:GLYCEROL'>GOL</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=3qnz FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=3qnz OCA], [https://pdbe.org/3qnz PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=3qnz RCSB], [https://www.ebi.ac.uk/pdbsum/3qnz PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=3qnz ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/TBB5_HUMAN TBB5_HUMAN] Tubulin is the major constituent of microtubules. It binds two moles of GTP, one at an exchangeable site on the beta chain and one at a non-exchangeable site on the alpha chain.
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== Publication Abstract from PubMed ==
Despite being the most abundant class of immunoglobulins in humans and playing central roles in the adaptive immune response, high-resolution structural data are still lacking for the antigen-binding region of human isotype A antibodies (IgAs). The crystal structures of a human Fab fragment of IgA1 in three different crystal forms are now reported. The three-dimensional organization is similar to those of other Fab classes, but FabA1 seems to be more rigid, being constrained by a hydrophobic core in the interface between the variable and constant domains of the heavy chain (VH-CH1) as well as by a disulfide bridge that connects the light and heavy chains, influencing the relative heavy/light-chain orientation. The crystal structure of the same antibody but with a G-isotype CH1 which is reported to display different antigen affinity has also been solved. The differential structural features reveal plausible mechanisms for constant/variable-domain long-distance effects whereby antibody class switching could alter antigen affinity.

Structure of a human IgA1 Fab fragment at 1.55 A resolution: potential effect of the constant domains on antigen-affinity modulation.,Correa A, Trajtenberg F, Obal G, Pritsch O, Dighiero G, Oppezzo P, Buschiazzo A Acta Crystallogr D Biol Crystallogr. 2013 Mar;69(Pt 3):388-97. doi:, 10.1107/S0907444912048664. Epub 2013 Feb 16. PMID:23519414<ref>PMID:23519414</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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== References ==
<references/>
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</StructureSection>
[[Category: Homo sapiens]]
[[Category: Large Structures]]
[[Category: Buschiazzo A]]
[[Category: Correa A]]
[[Category: Trajtenberg F]]