Experimental Data Snapshot

  • Resolution: 1.90 Å
  • R-Value Free: 0.250 
  • R-Value Work: 0.229 
  • R-Value Observed: 0.229 

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This is version 1.2 of the entry. See complete history


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, J.J.Wiley, D.C.

(1999) Proc Natl Acad Sci U S A 96: 8967-8972

  • DOI: https://doi.org/10.1073/pnas.96.16.8967
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    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.

  • Organizational Affiliation

    Department of Cellular and Molecular Biology, Howard Hughes Medical Institute, Harvard University, 7 Divinity Avenue, Cambridge, MA 02138, USA.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
A, B, C, D, E
A, B, C, D, E, F
155Influenza A virusMutation(s): 0 
Find proteins for P03437 (Influenza A virus (strain A/Aichi/2/1968 H3N2))
Explore P03437 
Go to UniProtKB:  P03437
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP03437
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 1.90 Å
  • R-Value Free: 0.250 
  • R-Value Work: 0.229 
  • R-Value Observed: 0.229 
  • Space Group: C 1 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 113.241α = 90
b = 48.877β = 103.26
c = 221.303γ = 90
Software Package:
Software NamePurpose
DENZOdata reduction
SCALEPACKdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2000-01-05
    Type: Initial release
  • Version 1.1: 2008-04-27
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance