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- NRAM_I82A2


P26143 - NRAM_I82A2

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Influenza A virus (strain A/Camel/Mongolia/1982 H1N1)
Reviewed - Annotation score: 4 out of 5- Experimental evidence at transcript leveli


Catalyzes the removal of terminal sialic acid residues from viral and cellular glycoconjugates. Cleaves off the terminal sialic acids on the glycosylated HA during virus budding to facilitate virus release. Additionally helps virus spread through the circulation by further removing sialic acids from the cell surface. These cleavages prevent self-aggregation and ensure the efficient spread of the progeny virus from cell to cell. Otherwise, infection would be limited to one round of replication. Described as a receptor-destroying enzyme because it cleaves a terminal sialic acid from the cellular receptors. May facilitate viral invasion of the upper airways by cleaving the sialic acid moities on the mucin of the airway epithelial cells. Likely to plays a role in the budding process through its association with lipid rafts during intracellular transport. May additionally display a raft-association independent effect on budding. Plays a role in the determination of host range restriction on replication and virulence. Sialidase activity in late endosome/lysosome traffic seems to enhance virus replication.

Catalytic activityi

Hydrolysis of alpha-(2->3)-, alpha-(2->6)-, alpha-(2->8)- glycosidic linkages of terminal sialic acid residues in oligosaccharides, glycoproteins, glycolipids, colominic acid and synthetic substrates.


Ca2+By similarityNote: Binds 1 Ca2+ ion per subunit.By similarity

Enzyme regulationi

Inhibited by the neuraminidase inhibitors zanamivir (Relenza) and oseltamivir (Tamiflu). These drugs interfere with the release of progeny virus from infected cells and are effective against all influenza strains. Resistance to neuraminidase inhibitors is quite rare.


Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Binding sitei101 – 1011SubstrateBy similarity

GO - Molecular functioni

  1. exo-alpha-(2->3)-sialidase activity Source: UniProtKB-EC
  2. exo-alpha-(2->6)-sialidase activity Source: UniProtKB-EC
  3. exo-alpha-(2->8)-sialidase activity Source: UniProtKB-EC
  4. metal ion binding Source: UniProtKB-KW

GO - Biological processi

  1. carbohydrate metabolic process Source: InterPro
Complete GO annotation...

Keywords - Molecular functioni

Glycosidase, Hydrolase

Keywords - Ligandi

Calcium, Metal-binding

Protein family/group databases

CAZyiGH34. Glycoside Hydrolase Family 34.

Names & Taxonomyi

Protein namesi
Recommended name:
Neuraminidase (EC:
Gene namesi
OrganismiInfluenza A virus (strain A/Camel/Mongolia/1982 H1N1)
Taxonomic identifieri387191 [NCBI]
Taxonomic lineageiVirusesssRNA negative-strand virusesOrthomyxoviridaeInfluenzavirus A
Virus hostiAves [TaxID: 8782]
Homo sapiens (Human) [TaxID: 9606]
Sus scrofa (Pig) [TaxID: 9823]

Subcellular locationi

Virion membrane By similarity. Host apical cell membrane By similarity; Single-pass type II membrane protein By similarity
Note: Preferentially accumulates at the apical plasma membrane in infected polarized epithelial cells, which is the virus assembly site. Uses lipid rafts for cell surface transport and apical sorting. In the virion, forms a mushroom-shaped spike on the surface of the membrane (By similarity).By similarity


Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Transmembranei‹1 – 18›18Helical; Signal-anchor for type II membrane proteinSequence AnalysisAdd
Topological domaini19 – ›103›85Virion surfaceSequence AnalysisAdd

GO - Cellular componenti

  1. host cell plasma membrane Source: UniProtKB-SubCell
  2. integral component of membrane Source: UniProtKB-KW
  3. virion membrane Source: UniProtKB-SubCell
Complete GO annotation...

Keywords - Cellular componenti

Host cell membrane, Host membrane, Membrane, Virion

PTM / Processingi

Molecule processing

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Chaini‹1 – ›103›103NeuraminidasePRO_0000078678Add

Amino acid modifications

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Glycosylationi27 – 271N-linked (GlcNAc...); by hostSequence Analysis
Glycosylationi41 – 411N-linked (GlcNAc...); by hostSequence Analysis
Glycosylationi46 – 461N-linked (GlcNAc...); by hostSequence Analysis
Glycosylationi51 – 511N-linked (GlcNAc...); by hostSequence Analysis
Glycosylationi71 – 711N-linked (GlcNAc...); by hostSequence Analysis

Post-translational modificationi

N-glycosylated.By similarity

Keywords - PTMi



Subunit structurei

Homotetramer.By similarity


3D structure databases

SMRiP26143. Positions 66-103.

Family & Domainsi


Intact N-terminus is essential for virion morphogenesis. Possess two apical sorting signals, one in the ectodomain, which is likely to be a glycan, and the other in the transmembrane domain. The transmembrane domain also plays a role in lipid raft association (By similarity).By similarity

Sequence similaritiesi

Belongs to the glycosyl hydrolase 34 family.Curated

Keywords - Domaini

Signal-anchor, Transmembrane, Transmembrane helix

Family and domain databases

Gene3Di2.120.10.10. 1 hit.
InterProiIPR001860. Glyco_hydro_34.
IPR011040. Sialidases.
[Graphical view]
PfamiPF00064. Neur. 1 hit.
[Graphical view]
SUPFAMiSSF50939. SSF50939. 1 hit.


Sequence statusi: Fragment.

P26143-1 [UniParc]FASTAAdd to Basket

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Mass (Da):11,253
Last modified:May 1, 1992 - v1

Experimental Info

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Non-terminal residuei1 – 11
Non-terminal residuei103 – 1031

Sequence databases

Select the link destinations:
Links Updated
M73976 mRNA. Translation: AAA16907.1.


Sequence databases

Select the link destinations:
Links Updated
M73976 mRNA. Translation: AAA16907.1 .

3D structure databases

ProteinModelPortali P26143.
SMRi P26143. Positions 66-103.
ModBasei Search...
MobiDBi Search...

Protein family/group databases

CAZyi GH34. Glycoside Hydrolase Family 34.

Protocols and materials databases

Structural Biology Knowledgebase Search...

Family and domain databases

Gene3Di 1 hit.
InterProi IPR001860. Glyco_hydro_34.
IPR011040. Sialidases.
[Graphical view ]
Pfami PF00064. Neur. 1 hit.
[Graphical view ]
SUPFAMi SSF50939. SSF50939. 1 hit.
ProtoNeti Search...


  1. "A reassortant H1N1 influenza A virus caused fatal epizootics among camels in Mongolia."
    Yamnikova S.S., Mandler J., Bekh-Ochir Z.H., Dachtzeren P., Ludwig S., Lvov D.K., Scholtissek C.
    Virology 197:558-563(1993) [PubMed] [Europe PMC] [Abstract]
  2. "Assembly and budding of influenza virus."
    Nayak D.P., Hui E.K., Barman S.
    Virus Res. 106:147-165(2004) [PubMed] [Europe PMC] [Abstract]
    Cited for: REVIEW.
  3. "Neuraminidase inhibitors for influenza."
    Moscona A.
    N. Engl. J. Med. 353:1363-1373(2005) [PubMed] [Europe PMC] [Abstract]
    Cited for: REVIEW.
  4. "Sialobiology of influenza: molecular mechanism of host range variation of influenza viruses."
    Suzuki Y.
    Biol. Pharm. Bull. 28:399-408(2005) [PubMed] [Europe PMC] [Abstract]
    Cited for: REVIEW.

Entry informationi

Entry nameiNRAM_I82A2
AccessioniPrimary (citable) accession number: P26143
Entry historyi
Integrated into UniProtKB/Swiss-Prot: May 1, 1992
Last sequence update: May 1, 1992
Last modified: January 7, 2015
This is version 89 of the entry and version 1 of the sequence. [Complete history]
Entry statusiReviewed (UniProtKB/Swiss-Prot)
Annotation programViral Protein Annotation Program



The influenza A 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.


  1. Glycosyl hydrolases
    Classification of glycosyl hydrolase families and list of entries
  2. SIMILARITY comments
    Index of protein domains and families

External Data

Dasty 3

Similar proteinsi

Links to similar proteins from the UniProt Reference Clusters (UniRef) at 100%, 90% and 50% sequence identity:
100%UniRef100 combines identical sequences and sub-fragments with 11 or more residues from any organism into Uniref entry.
90%UniRef90 is built by clustering UniRef100 sequences that have at least 90% sequence identity to, and 80% overlap with, the longest sequence (a.k.a seed sequence).
50%UniRef50 is built by clustering UniRef90 seed sequences that have at least 50% sequence identity to, and 80% overlap with, the longest sequence in the cluster.