View source for 1qu1

==CRYSTAL STRUCTURE OF EHA2 (23-185)==
<StructureSection load='1qu1' size='340' side='right' caption='[[1qu1]], [[Resolution|resolution]] 1.90&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[1qu1]] is a 6 chain structure with sequence from [http://en.wikipedia.org/wiki/Influenza_a_virus Influenza a virus]. The April 2006 RCSB PDB [http://pdb.rcsb.org/pdb/static.do?p=education_discussion/molecule_of_the_month/index.html Molecule of the Month] feature on ''Hemagglutinin''  by David S. Goodsell is [http://dx.doi.org/10.2210/rcsb_pdb/mom_2006_4 10.2210/rcsb_pdb/mom_2006_4]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1QU1 OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1QU1 FirstGlance]. <br>
</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=1qu1 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1qu1 OCA], [http://www.rcsb.org/pdb/explore.do?structureId=1qu1 RCSB], [http://www.ebi.ac.uk/pdbsum/1qu1 PDBsum]</span></td></tr>
</table>
== Function ==
[[http://www.uniprot.org/uniprot/HEMA_I68A0 HEMA_I68A0]] 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. 
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== Publication Abstract from PubMed ==
The structure of a stable recombinant ectodomain of influenza hemagglutinin HA(2) subunit, EHA(2) (23-185), defined by proteolysis studies of the intact bacterial-expressed ectodomain, was determined to 1.9-A resolution by using x-ray crystallography. The structure reveals a domain composed of N- and C-terminal residues that form an N cap terminating both the N-terminal alpha-helix and the central coiled coil. The N cap is formed by a conserved sequence, and part of it is found in the neutral pH conformation of HA. The C-terminal 23 residues of the ectodomain form a 72-A long nonhelical structure ordered to within 7 residues of the transmembrane anchor. The structure implies that continuous alpha helices are not required for membrane fusion at either the N or C termini. The difference in stability between recombinant molecules with and without the N cap sequences suggests that additional free energy for membrane fusion may become available after the formation of the central triple-stranded coiled coil and insertion of the fusion peptide into the target membrane.

N- and C-terminal residues combine in the fusion-pH influenza hemagglutinin HA(2) subunit to form an N cap that terminates the triple-stranded coiled coil.,Chen J, Skehel JJ, Wiley DC Proc Natl Acad Sci U S A. 1999 Aug 3;96(16):8967-72. PMID:10430879<ref>PMID:10430879</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>

==See Also==
*[[Hemagglutinin|Hemagglutinin]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Hemagglutinin]]
[[Category: Influenza a virus]]
[[Category: RCSB PDB Molecule of the Month]]
[[Category: Chen, J]]
[[Category: Skehel, J J]]
[[Category: Wiley, D C]]
[[Category: Low-ph]]
[[Category: Viral protein]]
[[Category: Virus/viral protein]]