View source for 1qac


==CHANGE IN DIMERIZATION MODE BY REMOVAL OF A SINGLE UNSATISFIED POLAR RESIDUE==
<StructureSection load='1qac' size='340' side='right'caption='[[1qac]], [[Resolution|resolution]] 1.80&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[1qac]] is a 2 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=1QAC OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1QAC 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]] 1.8&#8491;</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=1qac FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1qac OCA], [https://pdbe.org/1qac PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1qac RCSB], [https://www.ebi.ac.uk/pdbsum/1qac PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1qac ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/KV401_HUMAN KV401_HUMAN] V segment of the variable domain of immunoglobulins light chain that participates in the antigen recognition (PubMed:24600447). Immunoglobulins, also known as antibodies, are membrane-bound or secreted glycoproteins produced by B lymphocytes. In the recognition phase of humoral immunity, the membrane-bound immunoglobulins serve as receptors which, upon binding of a specific antigen, trigger the clonal expansion and differentiation of B lymphocytes into immunoglobulins-secreting plasma cells. Secreted immunoglobulins mediate the effector phase of humoral immunity, which results in the elimination of bound antigens (PubMed:20176268, PubMed:22158414). The antigen binding site is formed by the variable domain of one heavy chain, together with that of its associated light chain. Thus, each immunoglobulin has two antigen binding sites with remarkable affinity for a particular antigen. The variable domains are assembled by a process called V-(D)-J rearrangement and can then be subjected to somatic hypermutations which, after exposure to antigen and selection, allow affinity maturation for a particular antigen (PubMed:17576170, PubMed:20176268).<ref>PMID:17576170</ref> <ref>PMID:20176268</ref> <ref>PMID:22158414</ref> <ref>PMID:24600447</ref> 
== Evolutionary Conservation ==
[[Image:Consurf_key_small.gif|200px|right]]
Check<jmol>
  <jmolCheckbox>
    <scriptWhenChecked>; select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/qa/1qac_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=1qac ConSurf].
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== Publication Abstract from PubMed ==
The importance of unsatisfied hydrogen bonding potential on protein-protein interaction was studied. Two alternate modes of dimerization (conventional and flipped form) of an immunoglobulin light chain variable domain (V(L)) were previously identified. In the flipped form, interface residue Gln89 would have an unsatisfied hydrogen bonding potential. Removal of this Gln should render the flipped dimer as the more favorable quaternary form. High resolution crystallographic studies of the Q89A and Q89L mutants show, as we predicted, that these proteins indeed form flipped dimers with very similar interfaces. A small cavity is present in the Q89A mutant that is reflected in the approximately 100 times lower association constant than found for the Q89L mutant. The association constant of Q89A and Q89L proteins (4 x 10(6) M(-1) and &gt;10(8) M(-1)) are 10- and 1,000-fold higher than that of the wild-type protein that forms conventional dimers clearly showing the energetic reasons for the flipped dimer formation.

Change in dimerization mode by removal of a single unsatisfied polar residue located at the interface.,Pokkuluri PR, Cai X, Johnson G, Stevens FJ, Schiffer M Protein Sci. 2000 Sep;9(9):1852-5. PMID:11045631<ref>PMID:11045631</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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<div class="pdbe-citations 1qac" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Homo sapiens]]
[[Category: Large Structures]]
[[Category: Cai X]]
[[Category: Johnson G]]
[[Category: Pokkuluri PR]]
[[Category: Schiffer M]]
[[Category: Stevens FJ]]