ID   Q0A3L8_9INFA            Unreviewed;        97 AA.
AC   Q0A3L8;
DT   17-OCT-2006, integrated into UniProtKB/TrEMBL.
DT   17-OCT-2006, sequence version 1.
DT   05-DEC-2018, entry version 55.
DE   RecName: Full=Matrix protein 2 {ECO:0000256|HAMAP-Rule:MF_04069, ECO:0000256|RuleBase:RU361247, ECO:0000256|SAAS:SAAS01040803};
DE   AltName: Full=Proton channel protein M2 {ECO:0000256|HAMAP-Rule:MF_04069};
GN   Name=M2 {ECO:0000313|EMBL:ABI84715.1};
GN   Synonyms=M {ECO:0000256|HAMAP-Rule:MF_04069};
OS   Influenza A virus (A/turkey/Minnesota/1012/1990(H13N2)).
OC   Viruses; ssRNA viruses; ssRNA negative-strand viruses;
OC   Orthomyxoviridae; Alphainfluenzavirus.
OX   NCBI_TaxID=402492 {ECO:0000313|EMBL:ABI84715.1};
RN   [1] {ECO:0000313|EMBL:ABI84715.1}
RP   NUCLEOTIDE SEQUENCE.
RC   STRAIN=A/turkey/Minnesota/1012/1990 {ECO:0000313|EMBL:ABI84715.1};
RX   PubMed=16439620; DOI=10.1126/science.1121586;
RA   Obenauer J.C., Denson J., Mehta P.K., Su X., Mukatira S.,
RA   Finkelstein D.B., Xu X., Wang J., Ma J., Fan Y., Rakestraw K.M.,
RA   Webster R.G., Hoffmann E., Krauss S., Zheng J., Zhang Z., Naeve C.W.;
RT   "Large-scale sequence analysis of avian influenza isolates.";
RL   Science 311:1576-1580(2006).
CC   -!- FUNCTION: Forms a proton-selective ion channel that is necessary
CC       for the efficient release of the viral genome during virus entry.
CC       After 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
CC       to disrupt interactions between the viral ribonucleoprotein (RNP),
CC       matrix protein 1 (M1), and lipid bilayers, thereby freeing the
CC       viral genome from interaction with viral proteins and enabling RNA
CC       segments to migrate to the host cell nucleus, where influenza
CC       virus RNA transcription and replication occur. Also plays a role
CC       in viral proteins secretory pathway. Elevates the intravesicular
CC       pH of normally acidic compartments, such as trans-Golgi network,
CC       preventing newly formed hemagglutinin from premature switching to
CC       the fusion-active conformation. {ECO:0000256|HAMAP-Rule:MF_04069,
CC       ECO:0000256|SAAS:SAAS01040783}.
CC   -!- ACTIVITY REGULATION: The M2 protein from most influenza A strains
CC       is inhibited by amantadine and rimantadine, resulting in viral
CC       uncoating incapacity. Emergence of amantadine-resistant variants
CC       is usually rapid. {ECO:0000256|RuleBase:RU361247,
CC       ECO:0000256|SAAS:SAAS01073786}.
CC   -!- SUBUNIT: Homotetramer; composed of two disulfide-linked dimers
CC       held together by non-covalent interactions. May interact with
CC       matrix protein 1. {ECO:0000256|HAMAP-Rule:MF_04069,
CC       ECO:0000256|RuleBase:RU361247, ECO:0000256|SAAS:SAAS01040791}.
CC   -!- SUBCELLULAR LOCATION: Host apical cell membrane
CC       {ECO:0000256|HAMAP-Rule:MF_04069, ECO:0000256|SAAS:SAAS01040793};
CC       Single-pass type III membrane protein {ECO:0000256|HAMAP-
CC       Rule:MF_04069, ECO:0000256|SAAS:SAAS01040793}. Virion membrane
CC       {ECO:0000256|HAMAP-Rule:MF_04069}. Note=Abundantly expressed at
CC       the apical plasma membrane in infected polarized epithelial cells,
CC       in close proximity to budding and assembled virions. Minor
CC       component of virions (only 16-20 molecules/virion).
CC       {ECO:0000256|HAMAP-Rule:MF_04069}.
CC   -!- DOMAIN: Cytoplasmic tail plays an important role in virion
CC       assembly and morphogenesis. {ECO:0000256|HAMAP-Rule:MF_04069,
CC       ECO:0000256|RuleBase:RU361247}.
CC   -!- MISCELLANEOUS: When the channel is activated, one or more
CC       imidazole moities of His-37 probably become bi-protonated.
CC       {ECO:0000256|HAMAP-Rule:MF_04069}.
CC   -!- SIMILARITY: Belongs to the influenza viruses matrix protein M2
CC       family. {ECO:0000256|HAMAP-Rule:MF_04069,
CC       ECO:0000256|RuleBase:RU361247, ECO:0000256|SAAS:SAAS01040773}.
CC   -!- CAUTION: Lacks conserved residue(s) required for the propagation
CC       of feature annotation. {ECO:0000256|HAMAP-Rule:MF_04069}.
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DR   EMBL; CY014800; ABI84715.1; -; Other_RNA.
DR   GO; GO:0020002; C:host cell plasma membrane; IEA:UniProtKB-SubCell.
DR   GO; GO:0016021; C:integral component of membrane; IEA:UniProtKB-UniRule.
DR   GO; GO:0044385; C:integral to membrane of host cell; IEA:UniProtKB-UniRule.
DR   GO; GO:0055036; C:virion membrane; IEA:UniProtKB-UniRule.
DR   GO; GO:0005216; F:ion channel activity; IEA:UniProtKB-UniRule.
DR   GO; GO:0015078; F:proton transmembrane transporter activity; IEA:UniProtKB-UniRule.
DR   GO; GO:0039707; P:pore formation by virus in membrane of host cell; IEA:UniProtKB-UniRule.
DR   GO; GO:0051259; P:protein complex oligomerization; IEA:UniProtKB-UniRule.
DR   GO; GO:0039521; P:suppression by virus of host autophagy; IEA:UniProtKB-UniRule.
DR   HAMAP; MF_04069; INFV_M2; 1.
DR   InterPro; IPR002089; Flu_M2.
DR   Pfam; PF00599; Flu_M2; 1.
DR   ProDom; PD001031; Flu_M2; 1.
PE   3: Inferred from homology;
KW   Disulfide bond {ECO:0000256|HAMAP-Rule:MF_04069,
KW   ECO:0000256|SAAS:SAAS01040795};
KW   Host cell membrane {ECO:0000256|HAMAP-Rule:MF_04069,
KW   ECO:0000256|RuleBase:RU361247, ECO:0000256|SAAS:SAAS01040804};
KW   Host membrane {ECO:0000256|HAMAP-Rule:MF_04069,
KW   ECO:0000256|RuleBase:RU361247, ECO:0000256|SAAS:SAAS01040762};
KW   Host-virus interaction {ECO:0000256|HAMAP-Rule:MF_04069,
KW   ECO:0000256|SAAS:SAAS01040805};
KW   Hydrogen ion transport {ECO:0000256|HAMAP-Rule:MF_04069,
KW   ECO:0000256|RuleBase:RU361247, ECO:0000256|SAAS:SAAS01040774};
KW   Inhibition of host autophagy by virus {ECO:0000256|HAMAP-
KW   Rule:MF_04069, ECO:0000256|SAAS:SAAS01040755};
KW   Ion channel {ECO:0000256|HAMAP-Rule:MF_04069,
KW   ECO:0000256|RuleBase:RU361247, ECO:0000256|SAAS:SAAS01040776};
KW   Ion transport {ECO:0000256|HAMAP-Rule:MF_04069,
KW   ECO:0000256|RuleBase:RU361247, ECO:0000256|SAAS:SAAS01040807};
KW   Lipoprotein {ECO:0000256|HAMAP-Rule:MF_04069};
KW   Membrane {ECO:0000256|HAMAP-Rule:MF_04069,
KW   ECO:0000256|RuleBase:RU361247, ECO:0000256|SAAS:SAAS01040794,
KW   ECO:0000256|SAM:Phobius};
KW   Palmitate {ECO:0000256|HAMAP-Rule:MF_04069};
KW   Phosphoprotein {ECO:0000256|HAMAP-Rule:MF_04069};
KW   Signal-anchor {ECO:0000256|HAMAP-Rule:MF_04069,
KW   ECO:0000256|RuleBase:RU361247};
KW   Transmembrane {ECO:0000256|HAMAP-Rule:MF_04069,
KW   ECO:0000256|RuleBase:RU361247, ECO:0000256|SAAS:SAAS01040784,
KW   ECO:0000256|SAM:Phobius};
KW   Transmembrane helix {ECO:0000256|HAMAP-Rule:MF_04069,
KW   ECO:0000256|RuleBase:RU361247, ECO:0000256|SAAS:SAAS01040757,
KW   ECO:0000256|SAM:Phobius};
KW   Transport {ECO:0000256|HAMAP-Rule:MF_04069,
KW   ECO:0000256|RuleBase:RU361247, ECO:0000256|SAAS:SAAS01040788};
KW   Viral ion channel {ECO:0000256|HAMAP-Rule:MF_04069,
KW   ECO:0000256|SAAS:SAAS01040754};
KW   Virion {ECO:0000256|HAMAP-Rule:MF_04069,
KW   ECO:0000256|RuleBase:RU361247, ECO:0000256|SAAS:SAAS01040766}.
FT   TOPO_DOM      1     22       Virion surface. {ECO:0000256|HAMAP-Rule:
FT                                MF_04069}.
FT   TRANSMEM     26     48       Helical. {ECO:0000256|SAM:Phobius}.
FT   TOPO_DOM     44     97       Intravirion. {ECO:0000256|HAMAP-Rule:
FT                                MF_04069}.
FT   SITE         37     37       Essential for channel activity, possibly
FT                                by being protonated during channel
FT                                activation, and by forming the channel
FT                                gate and the selective filter.
FT                                {ECO:0000256|HAMAP-Rule:MF_04069}.
FT   SITE         41     41       Seems to be involved in pH gating.
FT                                {ECO:0000256|HAMAP-Rule:MF_04069}.
FT   MOD_RES      64     64       Phosphoserine; by host.
FT                                {ECO:0000256|HAMAP-Rule:MF_04069}.
FT   MOD_RES      82     82       Phosphoserine; by host.
FT                                {ECO:0000256|HAMAP-Rule:MF_04069}.
FT   LIPID        50     50       S-palmitoyl cysteine; by host.
FT                                {ECO:0000256|HAMAP-Rule:MF_04069}.
FT   DISULFID     17     17       Interchain (with Cys-17).
FT                                {ECO:0000256|HAMAP-Rule:MF_04069}.
FT   DISULFID     19     19       Interchain (with Cys-19).
FT                                {ECO:0000256|HAMAP-Rule:MF_04069}.
SQ   SEQUENCE   97 AA;  11136 MW;  3F4093895ED46301 CRC64;
     MSLLTEVETH TRSGWECRCS DSSDPLVIAA SIIGILHLIL WILDRLFFKC IYRRFKYGLK
     SGPSTEGVPE SMREEYQQEK QSAVDVDDGH FVNIELE
//