P17504 · HEMA_INBBE

Function

function

Binds to sialic acid-containing receptors on the cell surface, bringing about the attachment of the virus particle to the cell. 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 induce an irreversible conformational change in HA2, releasing the fusion hydrophobic peptide. Several trimers are required to form a competent fusion pore.

Miscellaneous

Major glycoprotein, comprises over 80% of the envelope proteins present in virus particle.
The extent of infection into host organism is determined by HA. Influenza viruses bud from the apical surface of polarized epithelial cells (e.g. bronchial epithelial cells) into lumen of lungs and are therefore usually pneumotropic. The reason is that HA is cleaved by tryptase clara which is restricted to lungs. However, HAs of H5 and H7 pantropic avian viruses subtypes can be cleaved by furin and subtilisin-type enzymes, allowing the virus to grow in other organs than lungs.
The influenza B genome consist of 8 RNA segments. Genetic variation of hemagglutinin and/or neuraminidase genes results in the emergence of new influenza strains. The mechanism of variation can be the result of point mutations or the result of genetic reassortment between segments of two different strains.

Features

Showing features for site.

TypeIDPosition(s)Description
Site362-363Cleavage; by host

GO annotations

AspectTerm
Cellular Componenthost cell plasma membrane
Cellular Componentmembrane
Cellular Componentviral envelope
Cellular Componentvirion membrane
Molecular Functionhost cell surface receptor binding
Biological Processendocytosis involved in viral entry into host cell
Biological Processfusion of virus membrane with host endosome membrane
Biological Processfusion of virus membrane with host plasma membrane
Biological Processviral budding from plasma membrane
Biological Processvirion attachment to host cell

Keywords

Names & Taxonomy

Protein names

Gene names

    • Name
      HA

Organism names

Accessions

  • Primary accession
    P17504

Subcellular Location

Virion membrane
; Single-pass type I membrane protein
Host apical cell membrane
; Single-pass type I membrane protein
Note: Targeted to the apical plasma membrane in epithelial polarized cells through a signal present in the transmembrane domain. Associated with glycosphingolipid- and cholesterol-enriched detergent-resistant lipid rafts.

Features

Showing features for topological domain, transmembrane.

TypeIDPosition(s)Description
Topological domain16-553Extracellular
Transmembrane554-574Helical
Topological domain575-585Cytoplasmic

Keywords

PTM/Processing

Features

Showing features for signal, chain, disulfide bond, glycosylation, lipidation.

TypeIDPosition(s)Description
Signal1-15
ChainPRO_000044054516-361Hemagglutinin HA1 chain
ChainPRO_000044054416-585Hemagglutinin
Disulfide bond19↔499Interchain (between HA1 and HA2 chains)
Glycosylation40N-linked (GlcNAc...) asparagine; by host
Glycosylation74N-linked (GlcNAc...) asparagine; by host
Disulfide bond75↔87
Disulfide bond109↔158
Glycosylation160N-linked (GlcNAc...) asparagine; by host
Glycosylation181N-linked (GlcNAc...) asparagine; by host
Glycosylation319N-linked (GlcNAc...) asparagine; by host
Glycosylation348N-linked (GlcNAc...) asparagine; by host
ChainPRO_0000039087363-585Hemagglutinin HA2 chain
Disulfide bond506↔510
Glycosylation507N-linked (GlcNAc...) asparagine; by host
Glycosylation533N-linked (GlcNAc...) asparagine; by host
Glycosylation546N-linked (GlcNAc...) asparagine; by host
Lipidation581S-palmitoyl cysteine; by host
Lipidation584S-palmitoyl cysteine; by host

Post-translational modification

Palmitoylated.
In natural infection, inactive HA is matured into HA1 and HA2 outside the cell by one or more trypsin-like, arginine-specific endoprotease secreted by the bronchial epithelial cells. One identified protease that may be involved in this process is secreted in lungs by club cells.

Keywords

PTM databases

Interaction

Subunit

Homotrimer of disulfide-linked HA1-HA2.

Structure

3D structure databases

Family & Domains

Sequence similarities

Belongs to the influenza viruses hemagglutinin family.

Keywords

Family and domain databases

Sequence

  • Sequence status
    Complete
  • Sequence processing
    The displayed sequence is further processed into a mature form.
  • Length
    585
  • Mass (Da)
    63,166
  • Last updated
    1990-08-01 v1
  • Checksum
    129987C8572F9176
MKAIIVLLMVVTSNADRICTGITSSNSPHVVKTATQGEVNVTGVIPLTTTPTKSHFANLKGTKTRGKLCPKCLNCTDLDVALGRPKCMGTIPSAKASILHEVKPVTSGCFPIMHDRTKIRQLPNLLRGYEHIRLSTHNVINAETAPGGPYKVGTSGSCPNVTNGNGFFATMAWAVPKNDNNKTATNPLTVEVPYICTEGEDQITVWGFHSDNEAQMVKLYGDSKPQKFTSSANGVTTHYVSQIGGFPNQAEDGGLPQSGRIVVDYMVQKSGKTGTITYQRGILLPQKVWCASGRSKVIKGSLPLIGERDCLHEKYGGLNKSKPYYTGEHAKAIGNCPIWVKTPLKLANGTKYRPPAKLLKERGFFGAIAGFLEGGWEGMIAGWHGYTSHGAHGVAVAADLKSTQEAINKITKNLNSLSELEVKNLQRLSGAMDELHNEILELDEKVDDLRADTISSQIELAVLLSNEGIINSEDEHLLALERKLKKMLGPSAVDIGNGCFETKHKCNQTCLDRIAAGTFNAGEFSLPTFDSLNITAASLNDDGLDNHTILLYYSTAASSLAVTLMIAIFIVYMVSRDNVSCSICL

Sequence databases

Nucleotide SequenceProtein SequenceMolecule TypeStatus
X53098
EMBL· GenBank· DDBJ
CAA37262.1
EMBL· GenBank· DDBJ
Genomic RNA

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