M2_I02A1
ID M2_I02A1 Reviewed; 90 AA.
AC Q6DPU3;
DT 13-NOV-2007, integrated into UniProtKB/Swiss-Prot.
DT 16-AUG-2004, sequence version 1.
DT 02-JUN-2021, entry version 59.
DE RecName: Full=Matrix protein 2;
DE AltName: Full=Proton channel protein M2;
DE Flags: Fragment;
GN Name=M;
OS Influenza A virus (strain A/Guinea fowl/Hong Kong/38/2002 H5N1 genotype
OS X0).
OC Viruses; Riboviria; Orthornavirae; Negarnaviricota; Polyploviricotina;
OC Insthoviricetes; Articulavirales; Orthomyxoviridae; Alphainfluenzavirus.
OX NCBI_TaxID=284208;
OH NCBI_TaxID=8782; Aves.
OH NCBI_TaxID=9685; Felis catus (Cat) (Felis silvestris catus).
OH NCBI_TaxID=9606; Homo sapiens (Human).
OH NCBI_TaxID=9691; Panthera pardus (Leopard) (Felis pardus).
OH NCBI_TaxID=9694; Panthera tigris (Tiger).
OH NCBI_TaxID=9823; Sus scrofa (Pig).
RN [1]
RP NUCLEOTIDE SEQUENCE [GENOMIC RNA].
RX PubMed=15241415; DOI=10.1038/nature02746;
RA Li K.S., Guan Y., Wang J., Smith G.J.D., Xu K.M., Duan L., Rahardjo A.P.,
RA Puthavathana P., Buranathai C., Nguyen T.D., Estoepangestie A.T.S.,
RA Chaisingh A., Auewarakul P., Long H.T., Hanh N.T.H., Webby R.J.,
RA Poon L.L.M., Chen H., Shortridge K.F., Yuen K.Y., Webster R.G.,
RA Peiris J.S.M.;
RT "Genesis of a highly pathogenic and potentially pandemic H5N1 influenza
RT virus in eastern Asia.";
RL Nature 430:209-213(2004).
CC -!- FUNCTION: Forms a proton-selective ion channel that is necessary for
CC the efficient release of the viral genome during virus entry. After
CC attaching to the cell surface, the virion enters the cell by
CC endocytosis. Acidification of the endosome triggers M2 ion channel
CC activity. The influx of protons into virion interior is believed to
CC disrupt interactions between the viral ribonucleoprotein (RNP), matrix
CC protein 1 (M1), and lipid bilayers, thereby freeing the viral genome
CC from interaction with viral proteins and enabling RNA segments to
CC migrate to the host cell nucleus, where influenza virus RNA
CC transcription and replication occur. Also plays a role in viral
CC proteins secretory pathway. Elevates the intravesicular pH of normally
CC acidic compartments, such as trans-Golgi network, preventing newly
CC formed hemagglutinin from premature switching to the fusion-active
CC conformation (By similarity). {ECO:0000250}.
CC -!- ACTIVITY REGULATION: The M2 protein from most influenza A strains is
CC inhibited by amantadine and rimantadine, resulting in viral uncoating
CC incapacity. Emergence of amantadine-resistant variants is usually
CC rapid.
CC -!- SUBUNIT: Homotetramer; composed of two disulfide-linked dimers held
CC together by non-covalent interactions (By similarity). May interact
CC with matrix protein 1. {ECO:0000250}.
CC -!- SUBCELLULAR LOCATION: Virion membrane. Host apical cell membrane;
CC Single-pass type III membrane protein. Note=Abundantly expressed at the
CC apical plasma membrane in infected polarized epithelial cells, in close
CC proximity to budding and assembled virions. Minor component of virions
CC (only 16-20 molecules/virion) (By similarity). {ECO:0000250}.
CC -!- ALTERNATIVE PRODUCTS:
CC Event=Alternative splicing; Named isoforms=2;
CC Comment=Only the first 9 residues are shared by the 2 isoforms.;
CC Name=M2;
CC IsoId=Q6DPU3-1; Sequence=Displayed;
CC Name=M1;
CC IsoId=Q6DPU2-1; Sequence=External;
CC -!- DOMAIN: Cytoplasmic tail plays an important role in virion assembly and
CC morphogenesis. {ECO:0000250}.
CC -!- MISCELLANEOUS: When the channel is activated, one or more imidazole
CC moieties of His-30 probably become bi-protonated.
CC -!- SIMILARITY: Belongs to the influenza viruses matrix protein M2 family.
CC {ECO:0000305}.
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DR EMBL; AY651399; AAT70550.1; -; Genomic_RNA.
DR SMR; Q6DPU3; -.
DR GO; GO:0020002; C:host cell plasma membrane; IEA:UniProtKB-SubCell.
DR GO; GO:0016021; C:integral component of membrane; IEA:UniProtKB-KW.
DR GO; GO:0044385; C:integral to membrane of host cell; IEA:UniProtKB-KW.
DR GO; GO:0055036; C:virion membrane; IEA:UniProtKB-SubCell.
DR GO; GO:0005216; F:ion channel activity; IEA:UniProtKB-KW.
DR GO; GO:0015078; F:proton transmembrane transporter activity; IEA:InterPro.
DR GO; GO:0039707; P:pore formation by virus in membrane of host cell; IEA:UniProtKB-KW.
DR GO; GO:0051259; P:protein complex oligomerization; IEA:UniProtKB-KW.
DR InterPro; IPR002089; Flu_M2.
DR Pfam; PF00599; Flu_M2; 1.
PE 3: Inferred from homology;
KW Alternative splicing; Disulfide bond; Host cell membrane; Host membrane;
KW Hydrogen ion transport; Ion channel; Ion transport; Lipoprotein; Membrane;
KW Palmitate; Phosphoprotein; Signal-anchor; Transmembrane;
KW Transmembrane helix; Transport; Viral ion channel; Virion.
FT CHAIN <1..90
FT /note="Matrix protein 2"
FT /id="PRO_0000311626"
FT TOPO_DOM <1..15
FT /note="Virion surface"
FT /evidence="ECO:0000255"
FT TRANSMEM 16..36
FT /note="Helical"
FT /evidence="ECO:0000255"
FT TOPO_DOM 37..90
FT /note="Intravirion"
FT /evidence="ECO:0000255"
FT REGION 53..76
FT /note="Disordered"
FT /evidence="ECO:0000256|SAM:MobiDB-lite"
FT SITE 30
FT /note="Essential for channel activity, seems to be
FT protonated during channel activation, and may play a role
FT in the channel gating and selectivity"
FT /evidence="ECO:0000250"
FT SITE 34
FT /note="Seems to be involved in pH gating"
FT /evidence="ECO:0000250"
FT MOD_RES 57
FT /note="Phosphoserine; by host"
FT /evidence="ECO:0000250"
FT LIPID 43
FT /note="S-palmitoyl cysteine; by host"
FT /evidence="ECO:0000250"
FT DISULFID 10
FT /note="Interchain (with C-17)"
FT /evidence="ECO:0000250"
FT DISULFID 12
FT /note="Interchain (with C-19)"
FT /evidence="ECO:0000250"
FT NON_TER 1
SQ SEQUENCE 90 AA; 10285 MW; D84730880BBFE51B CRC64;
ETPTRTGWEC KCSDSSDPLV VAASIIGILH LILWILDRLF FKCIYRRLKY GLKRGPSTGG
VPESMREEYR QEQQSAVDVD DGHFVNIELE
