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==Structure and receptor binding prefereneces of recombinant human A(H3N2) virus hemagglutinins==
<StructureSection load='4wea' size='340' side='right' caption='[[4wea]], [[Resolution|resolution]] 2.20&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[4wea]] is a 1 chain structure. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=4WEA OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=4WEA FirstGlance]. <br>
</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=NAG:N-ACETYL-D-GLUCOSAMINE'>NAG</scene>, <scene name='pdbligand=SIA:O-SIALIC+ACID'>SIA</scene></td></tr>
<tr id='related'><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat">[[4we4|4we4]], [[4we5|4we5]], [[4we6|4we6]], [[4we7|4we7]], [[4we8|4we8]], [[4we9|4we9]]</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=4wea FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4wea OCA], [http://pdbe.org/4wea PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=4wea RCSB], [http://www.ebi.ac.uk/pdbsum/4wea PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=4wea ProSAT]</span></td></tr>
</table>
== Function ==
[[http://www.uniprot.org/uniprot/R9U684_9INFA R9U684_9INFA]] Binds to sialic acid-containing receptors on the cell surface, bringing about the attachment of the virus particle to the cell. This attachment induces virion internalization of about two third of the virus particles through clathrin-dependent endocytosis and about one third through a clathrin- and caveolin-independent pathway. Plays a major role in the determination of host range restriction and virulence. Class I viral fusion protein. Responsible for penetration of the virus into the cell cytoplasm by mediating the fusion of the membrane of the endocytosed virus particle with the endosomal membrane. Low pH in endosomes induces an irreversible conformational change in HA2, releasing the fusion hydrophobic peptide. Several trimers are required to form a competent fusion pore (By similarity).[SAAS:SAAS000149_004_327643][RuleBase:RU003324] 
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== Publication Abstract from PubMed ==
A(H3N2) influenza viruses have circulated in humans since 1968, and antigenic drift of the hemagglutinin (HA) protein continues to be a driving force that allows the virus to escape the human immune response. Since the major antigenic sites of the HA overlap into the receptor binding site (RBS) of the molecule, the virus constantly struggles to effectively adapt to host immune responses, without compromising its functionality. Here, we have structurally assessed the evolution of the A(H3N2) virus HA RBS, using an established recombinant expression system. Glycan binding specificities of nineteen A(H3N2) influenza virus HAs, each a component of the seasonal influenza vaccine between 1968 and 2012, were analyzed. Results suggest that while its receptor-binding site has evolved from one that can bind a broad range of human receptor analogs to one with a more restricted binding profile for longer glycans, the virus continues to circulate and transmit efficiently among humans.

Structure and receptor binding preferences of recombinant human A(H3N2) virus hemagglutinins.,Yang H, Carney PJ, Chang JC, Guo Z, Villanueva JM, Stevens J Virology. 2015 Jan 21;477C:18-31. doi: 10.1016/j.virol.2014.12.024. PMID:25617824<ref>PMID:25617824</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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==See Also==
*[[Hemagglutinin|Hemagglutinin]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Carney, P J]]
[[Category: Chang, J C]]
[[Category: Guo, Z]]
[[Category: Stevens, J]]
[[Category: Villanueva, J M]]
[[Category: Yang, H]]
[[Category: H3n2]]
[[Category: Hemagglutinin]]
[[Category: Influenza virus]]