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P26143 (NRAM_I82A2) Reviewed, UniProtKB/Swiss-Prot

Last modified February 19, 2014. Version 84. Feed History...

Clusters with 100%, 90%, 50% identity | Documents (2) | Third-party data text xml rdf/xml gff fasta
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Names and origin

Protein namesRecommended name:

Gene names
OrganismInfluenza A virus (strain A/Camel/Mongolia/1982 H1N1)
Taxonomic identifier387191 [NCBI]
Taxonomic lineageVirusesssRNA negative-strand virusesOrthomyxoviridaeInfluenzavirus A
Virus hostAves [TaxID: 8782]
Homo sapiens (Human) [TaxID: 9606]
Sus scrofa (Pig) [TaxID: 9823]

Protein attributes

Sequence length103 AA.
Sequence statusFragment.
Protein existenceInferred from homology

General annotation (Comments)


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 activity

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.


Binds 1 calcium ion By similarity.

Enzyme regulation

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.

Subunit structure

Homotetramer By similarity.

Subcellular location

Virion membrane By similarity. Host apical cell membrane; 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.


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.

Post-translational modification

N-glycosylated By similarity.


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.

Sequence similarities

Belongs to the glycosyl hydrolase 34 family.

Sequence annotation (Features)

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifier

Molecule processing

Chain‹1 – ›103›103Neuraminidase


Transmembrane‹1 – 18›18Helical; Signal-anchor for type II membrane protein; Potential
Topological domain19 – ›103›85Virion surface Potential


Binding site1011Substrate Potential

Amino acid modifications

Glycosylation271N-linked (GlcNAc...); by host Potential
Glycosylation411N-linked (GlcNAc...); by host Potential
Glycosylation461N-linked (GlcNAc...); by host Potential
Glycosylation511N-linked (GlcNAc...); by host Potential
Glycosylation711N-linked (GlcNAc...); by host Potential

Experimental info

Non-terminal residue11
Non-terminal residue1031


Sequence LengthMass (Da)Tools
P26143 [UniParc].

Last modified May 1, 1992. Version 1.
Checksum: F8474BC2B3D3B310

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[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.


Sequence databases

M73976 mRNA. Translation: AAA16907.1.

3D structure databases

SMRP26143. Positions 66-103.

Protein family/group databases

CAZyGH34. Glycoside Hydrolase Family 34.

Protocols and materials databases


Family and domain databases

Gene3D2.120.10.10. 1 hit.
InterProIPR001860. Glyco_hydro_34.
IPR011040. Sialidases.
[Graphical view]
PfamPF00064. Neur. 1 hit.
[Graphical view]
SUPFAMSSF50939. SSF50939. 1 hit.

Entry information

Entry nameNRAM_I82A2
AccessionPrimary (citable) accession number: P26143
Entry history
Integrated into UniProtKB/Swiss-Prot: May 1, 1992
Last sequence update: May 1, 1992
Last modified: February 19, 2014
This is version 84 of the entry and version 1 of the sequence. [Complete history]
Entry statusReviewed (UniProtKB/Swiss-Prot)
Annotation programViral Protein Annotation Program

Relevant documents


Index of protein domains and families

Glycosyl hydrolases

Classification of glycosyl hydrolase families and list of entries