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122  structures 62  species 0  interactions 64  sequences 1  architecture

Family: HN (PF00423)

Summary: Haemagglutinin-neuraminidase

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This is the Wikipedia entry entitled "Glycoside hydrolase family 83". More...

Glycoside hydrolase family 83 Edit Wikipedia article

This page is based on a Wikipedia article. The text is available under the Creative Commons Attribution/Share-Alike License.

This is the Wikipedia entry entitled "Hemagglutinin-neuraminidase". More...

Hemagglutinin-neuraminidase Edit Wikipedia article

Hemagglutinin-neuraminidase, Paramyxoviridae
PDB 1usr EBI.jpg
Structure of the sialic acid binding site in Newcastle disease virus hemagglutinin-neuraminidase.[1]
Pfam clanCL0434

Hemagglutinin-neuraminidase refers to a single viral protein that has both hemagglutinin and (endo) neuraminidase EC activity. This is in contrast to the proteins found in influenza, where both functions exist but in two separate proteins. Its neuraminidase domain has the CAZy designation glycoside hydrolase family 83 (GH83).[2]

It does show a structural similarity to influenza viral neuraminidase and has a six-bladed beta-propeller structure.[3] This Pfam entry also matches measles hemagglutinin (cd15467), which has a "dead" neuraminidase part repurposed as a receptor binding site.[4]

Hemagglutinin-neuraminidase allows the virus to stick to a potential host cell, and cut itself loose if necessary. Hemagglutinin-neuraminidase can be found in a variety of paramyxoviruses including mumps virus, human parainfluenza virus 3, and the avian pathogen Newcastle disease virus.

Types include:

Hemagglutinin-neuraminidase inhibitors have been investigated and suggest that there may applications for human use in the future.[5]


  1. ^ Zaitsev V, von Itzstein M, Groves D, et al. (April 2004). "Second sialic acid binding site in Newcastle disease virus hemagglutinin-neuraminidase: implications for fusion". J. Virol. 78 (7): 3733–41. doi:10.1128/JVI.78.7.3733-3741.2004. PMC 371092. PMID 15016893.
  2. ^ Yuan P, Thompson TB, Wurzburg BA, Paterson RG, Lamb RA, Jardetzky TS (2005). "Structural studies of the parainfluenza virus 5 hemagglutinin-neuraminidase tetramer in complex with its receptor, sialyllactose". Structure. 13 (5): 803–15. doi:10.1016/j.str.2005.02.019. PMID 15893670.
  3. ^ Lawrence MC, Borg NA, Streltsov VA, et al. (January 2004). "Structure of the haemagglutinin-neuraminidase from human parainfluenza virus type III". J. Mol. Biol. 335 (5): 1343–57. doi:10.1016/j.jmb.2003.11.032. PMID 14729348.
  4. ^ Colf, LA; Juo, ZS; Garcia, KC (December 2007). "Structure of the measles virus hemagglutinin". Nature Structural & Molecular Biology. 14 (12): 1227–8. doi:10.1038/nsmb1342. PMID 18026116.
  5. ^ Alymova IV, Taylor G, Takimoto T, et al. (May 2004). "Efficacy of novel hemagglutinin-neuraminidase inhibitors BCX 2798 and BCX 2855 against human parainfluenza viruses in vitro and in vivo". Antimicrob. Agents Chemother. 48 (5): 1495–502. doi:10.1128/AAC.48.5.1495-1502.2004. PMC 400544. PMID 15105096.

This page is based on a Wikipedia article. The text is available under the Creative Commons Attribution/Share-Alike License.

This tab holds the annotation information that is stored in the Pfam database. As we move to using Wikipedia as our main source of annotation, the contents of this tab will be gradually replaced by the Wikipedia tab.

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External database links

This tab holds annotation information from the InterPro database.

InterPro entry IPR000665

This entry represents the haemagglutinin-neuraminidase (HN) glycoprotein found in a variety of paramyxoviruses (negative-stranded RNA viruses), including Mumps virus, Human parainfluenza virus 3, and the avian pathogen Newcastle disease virus. It also includes hemagglutinin glycoproteins from Morbiliviruses, a genus belonging to the Paramyxoviridae family that includes the Measles virus. Morbiliviruses hemagglutinins have no neuraminidase activity [ PUBMED:18026116 ].

HN is a multi-functional protein with three distinct functions: a receptor-binding (haemagglutinin) activity, a receptor-destroying (neuraminidase) activity, and a membrane fusion activity that fuses the viral envelope to the host cell membrane in order to infect the cell.

Gene Ontology

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Domain organisation

Below is a listing of the unique domain organisations or architectures in which this domain is found. More...

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Pfam Clan

This family is a member of clan Sialidase (CL0434), which has the following description:

This superfamily includes sialidases enzymes. Several viruses use sialic acid as a cell surface receptor for host invasion. These viruses then have cell surface neuraminidase enzymes to cleave sialic acid from cell surface proteins allowing them to leave the host cell after replication. This superfamily are composed of six beta-sheets that form a six-fold beta-propeller structure. Many members of this superfamily contain BNR sequence motifs Pfam:PF02012.

The clan contains the following 16 members:

BNR BNR_2 BNR_3 BNR_4 BNR_6 End_beta_barrel End_beta_propel Fungal_lectin HN Mcl1_mid Neur Neuraminidase OLF Phytase PSII_BNR Sortilin-Vps10


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Curation and family details

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Seed source: Pfam-B_171 (release 1.0)
Previous IDs: none
Type: Repeat
Sequence Ontology: SO:0001068
Author: Finn RD
Number in seed: 7
Number in full: 64
Average length of the domain: 544.70 aa
Average identity of full alignment: 21 %
Average coverage of the sequence by the domain: 88.06 %

HMM information View help on HMM parameters

HMM build commands:
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 57096847 -E 1000 --cpu 4 HMM pfamseq
Model details:
Parameter Sequence Domain
Gathering cut-off 24.4 24.4
Trusted cut-off 38.5 59.7
Noise cut-off 21.4 21.2
Model length: 542
Family (HMM) version: 21
Download: download the raw HMM for this family

Species distribution

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Colour assignments

Archea Archea Eukaryota Eukaryota
Bacteria Bacteria Other sequences Other sequences
Viruses Viruses Unclassified Unclassified
Viroids Viroids Unclassified sequence Unclassified sequence


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For those sequences which have a structure in the Protein DataBank, we use the mapping between UniProt, PDB and Pfam coordinate systems from the PDBe group, to allow us to map Pfam domains onto UniProt sequences and three-dimensional protein structures. The table below shows the structures on which the HN domain has been found. There are 122 instances of this domain found in the PDB. Note that there may be multiple copies of the domain in a single PDB structure, since many structures contain multiple copies of the same protein sequence.

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