Legends: 1, ACT_SITE Charge relay system. {ECO:0000255|PROSITE-ProRule:PRU01027}; 2, S-palmitoyl cysteine; by host. {ECO:0000250}; 3, N-linked (GlcNAc...); by host. {ECO:0000255}; 4, CHAIN Capsid protein. {ECO:0000250}; 5, CHAIN E3 protein. {ECO:0000250}; 6, SIGNAL Not cleaved. {ECO:0000255}; 7, CHAIN E2 envelope glycoprotein. {ECO:0000250}; 8, CHAIN 6K protein. {ECO:0000250}; 9, CHAIN E1 envelope glycoprotein. {ECO:0000250}; 10, TOPO_DOM Extracellular. {ECO:0000255}; 11, TRANSMEM Helical. {ECO:0000255}; 12, TOPO_DOM Cytoplasmic. {ECO:0000255}; 13, Peptidase S3. {ECO:0000255|PROSITE- ProRule:PRU01027}; 14, REGION Intrinsically disordered, in contact with genomic RNA in nucleocapsid. {ECO:0000255}; 15, REGION Ribosome-binding. {ECO:0000250}; 16, REGION Transient transmembrane before p62-6K protein processing. {ECO:0000255}; 17, REGION E1 fusion peptide loop. {ECO:0000250}; 18, SITE Cleavage; by capsid protein. {ECO:0000250}; 19, SITE Cleavage; by host furin. {ECO:0000250}; 20, SITE Cleavage; by host signal peptidase. {ECO:0000250}; 21, ipfam:Alpha_E3_glycop [T]; 22, iprf:ALPHAVIRUS_CP [T]; 23, ipfam:Peptidase_S3 [T].
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ID POLS_MIDDV Reviewed; 1258 AA.
AC Q80S27;
DT 30-MAY-2006, integrated into UniProtKB/Swiss-Prot.
DT 01-JUN-2003, sequence version 1.
DT 05-OCT-2016, entry version 78.
DE RecName: Full=Structural polyprotein;
DE AltName: Full=p130;
DE Contains:
DE RecName: Full=Capsid protein;
DE EC=3.4.21.-;
DE AltName: Full=Coat protein;
DE Short=C;
DE Contains:
DE RecName: Full=p62;
DE AltName: Full=E3/E2;
DE Contains:
DE RecName: Full=E3 protein;
DE AltName: Full=Spike glycoprotein E3;
DE Contains:
DE RecName: Full=E2 envelope glycoprotein;
DE AltName: Full=Spike glycoprotein E2;
DE Contains:
DE RecName: Full=6K protein;
DE Contains:
DE RecName: Full=E1 envelope glycoprotein;
DE AltName: Full=Spike glycoprotein E1;
OS Middelburg virus.
OC Viruses; ssRNA viruses; ssRNA positive-strand viruses, no DNA stage;
OC Togaviridae; Alphavirus.
OX NCBI_TaxID=11023;
OH NCBI_TaxID=7158; Aedes.
OH NCBI_TaxID=149459; Mansonia.
OH NCBI_TaxID=9940; Ovis aries (Sheep).
RN [1]
RP NUCLEOTIDE SEQUENCE.
RA Kinney R.M., Pfeffer M.;
RT "Nucleotide sequence analyses of the 26S mRNAs of viruses of the genus
RT Alphavirus.";
RL Submitted (JAN-2001) to the EMBL/GenBank/DDBJ databases.
CC -!- FUNCTION: Capsid protein possesses a protease activity that
CC results in its autocatalytic cleavage from the nascent structural
CC protein. Following its self-cleavage, the capsid protein
CC transiently associates with ribosomes, binds to viral RNA and
CC rapidly assembles into icosaedric core particles. The resulting
CC nucleocapsid eventually associates with the cytoplasmic domain of
CC E2 at the cell membrane, leading to budding and formation of
CC mature virions. New virions attach to target cells, and after
CC endocytosis their membrane fuses with the target cell membrane.
CC This leads to the release of the nucleocapsid into the cytoplasm,
CC followed by an uncoating event necessary for the genomic RNA to
CC become accessible. The uncoating might be triggered by the
CC interaction of capsid proteins with ribosomes. Binding of
CC ribosomes would release the genomic RNA since the same region is
CC genomic RNA-binding and ribosome-binding (By similarity).
CC {ECO:0000250}.
CC -!- FUNCTION: E3 protein's function is unknown. {ECO:0000250}.
CC -!- FUNCTION: E2 is responsible for viral attachment to target host
CC cell, by binding to the cell receptor. Synthesized as a p62
CC precursor which is processed by furin at the cell membrane just
CC before virion budding, giving rise to E2-E1 heterodimer. The p62-
CC E1 heterodimer is stable, whereas E2-E1 is unstable and dissociate
CC at low pH. p62 is processed at the last step, presumably to avoid
CC E1 fusion activation before its final export to cell surface. E2
CC C-terminus contains a transitory transmembrane that would be
CC disrupted by palmitoylation, resulting in reorientation of the C-
CC terminal tail from lumenal to cytoplasmic side. This step is
CC critical since E2 C-terminus is involved in budding by interacting
CC with capsid proteins. This release of E2 C-terminus in cytoplasm
CC occurs lately in protein export, and precludes premature assembly
CC of particles at the endoplasmic reticulum membrane (By
CC similarity). {ECO:0000250}.
CC -!- FUNCTION: 6K is a constitutive membrane protein involved in virus
CC glycoprotein processing, cell permeabilization, and the budding of
CC viral particles. Disrupts the calcium homeostasis of the cell,
CC probably at the endoplasmic reticulum level. This leads to
CC cytoplasmic calcium elevation. Because of its lipophilic
CC properties, the 6K protein is postulated to influence the
CC selection of lipids that interact with the transmembrane domains
CC of the glycoproteins, which, in turn, affects the deformability of
CC the bilayer required for the extreme curvature that occurs as
CC budding proceeds. Present in low amount in virions, about 3%
CC compared to viral glycoproteins (By similarity). {ECO:0000250}.
CC -!- FUNCTION: E1 is a class II viral fusion protein. Fusion activity
CC is inactive as long as E1 is bound to E2 in mature virion. After
CC virus attachment to target cell and endocytosis, acidification of
CC the endosome would induce dissociation of E1/E2 heterodimer and
CC concomitant trimerization of the E1 subunits. This E1 trimer is
CC fusion active, and promotes release of viral nucleocapsid in
CC cytoplasm after endosome and viral membrane fusion. Efficient
CC fusion requires the presence of cholesterol and sphingolipid in
CC the target membrane (By similarity). {ECO:0000250}.
CC -!- SUBUNIT: p62 and E1 form a heterodimer shortly after synthesis.
CC Processing of p62 into E2 and E3 results in a heterodimer of E2
CC and E1. Spike at virion surface are constituted of three E2-E1
CC heterodimers. After target cell attachment and endocytosis, E1
CC change conformation to form homotrimers (By similarity).
CC {ECO:0000250}.
CC -!- SUBCELLULAR LOCATION: Capsid protein: Virion {ECO:0000250}. Host
CC cytoplasm {ECO:0000250}.
CC -!- SUBCELLULAR LOCATION: p62: Virion membrane {ECO:0000250}; Single-
CC pass type I membrane protein {ECO:0000250}. Host cell membrane
CC {ECO:0000250}; Single-pass type I membrane protein {ECO:0000250}.
CC -!- SUBCELLULAR LOCATION: E2 envelope glycoprotein: Virion membrane
CC {ECO:0000250}; Single-pass type I membrane protein {ECO:0000250}.
CC Host cell membrane {ECO:0000250}; Single-pass type I membrane
CC protein {ECO:0000250}.
CC -!- SUBCELLULAR LOCATION: E1 envelope glycoprotein: Virion membrane
CC {ECO:0000250}; Single-pass type I membrane protein {ECO:0000250}.
CC Host cell membrane {ECO:0000250}; Single-pass type I membrane
CC protein {ECO:0000250}.
CC -!- SUBCELLULAR LOCATION: 6K protein: Host cell membrane
CC {ECO:0000250}; Multi-pass membrane protein {ECO:0000250}. Virion
CC membrane {ECO:0000250}; Multi-pass membrane protein {ECO:0000250}.
CC -!- PTM: Specific enzymatic cleavages in vivo yield mature proteins.
CC Capsid protein is auto-cleaved during polyprotein translation,
CC unmasking p62 signal peptide. The remaining polyprotein is then
CC targeted to the endoplasmic reticulum, where host signal peptidase
CC cleaves it into p62, 6K and E1 proteins. p62 is further processed
CC to mature E3 and E2 by host furin in trans-Golgi vesicle (By
CC similarity). {ECO:0000250}.
CC -!- PTM: E2 and 6K are palmitoylated via thioester bonds.
CC {ECO:0000250}.
CC -!- MISCELLANEOUS: Structural polyprotein is translated from a
CC subgenomic RNA synthesized during togavirus replication.
CC -!- SIMILARITY: Contains 1 peptidase S3 domain. {ECO:0000255|PROSITE-
CC ProRule:PRU01027}.
DR EMBL; AF339486; AAO33343.1; -; Genomic_RNA.
DR ProteinModelPortal; Q80S27; -.
DR MEROPS; S03.001; -.
DR GO; GO:0030430; C:host cell cytoplasm; IEA:UniProtKB-SubCell.
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:0039619; C:T=4 icosahedral viral capsid; IEA:UniProtKB-KW.
DR GO; GO:0055036; C:virion membrane; IEA:UniProtKB-SubCell.
DR GO; GO:0004252; F:serine-type endopeptidase activity; IEA:InterPro.
DR GO; GO:0005198; F:structural molecule activity; IEA:InterPro.
DR GO; GO:0039654; P:fusion of virus membrane with host endosome membrane; IEA:UniProtKB-KW.
DR GO; GO:0019062; P:virion attachment to host cell; IEA:UniProtKB-KW.
DR Gene3D; 2.60.40.350; -; 1.
DR Gene3D; 2.60.98.10; -; 3.
DR InterPro; IPR002548; Alpha_E1_glycop.
DR InterPro; IPR000936; Alpha_E2_glycop.
DR InterPro; IPR002533; Alpha_E3_glycop.
DR InterPro; IPR000336; Flavivir/Alphavir_Ig-like.
DR InterPro; IPR011998; Glycoprot_cen/dimer.
DR InterPro; IPR013754; GlyE_dim.
DR InterPro; IPR014756; Ig_E-set.
DR InterPro; IPR009003; Peptidase_S1_PA.
DR InterPro; IPR000930; Peptidase_S3.
DR Pfam; PF01589; Alpha_E1_glycop; 1.
DR Pfam; PF00943; Alpha_E2_glycop; 1.
DR Pfam; PF01563; Alpha_E3_glycop; 1.
DR Pfam; PF00944; Peptidase_S3; 1.
DR PRINTS; PR00798; TOGAVIRIN.
DR SUPFAM; SSF50494; SSF50494; 1.
DR SUPFAM; SSF56983; SSF56983; 1.
DR SUPFAM; SSF81296; SSF81296; 1.
DR PROSITE; PS51690; ALPHAVIRUS_CP; 1.
PE 3: Inferred from homology;
KW Capsid protein; Cleavage on pair of basic residues; Disulfide bond;
KW Fusion of virus membrane with host endosomal membrane;
KW Fusion of virus membrane with host membrane; Glycoprotein;
KW Host cell membrane; Host cytoplasm; Host membrane;
KW Host-virus interaction; Hydrolase; Lipoprotein; Membrane; Palmitate;
KW Protease; Serine protease; Signal; T=4 icosahedral capsid protein;
KW Transmembrane; Transmembrane helix; Viral attachment to host cell;
KW Viral penetration into host cytoplasm; Virion;
KW Virus entry into host cell.
FT CHAIN 1 271 Capsid protein. {ECO:0000250}.
FT /FTId=PRO_0000238748.
FT CHAIN 272 758 p62. {ECO:0000250}.
FT /FTId=PRO_0000238749.
FT CHAIN 272 337 E3 protein. {ECO:0000250}.
FT /FTId=PRO_0000238750.
FT SIGNAL 272 287 Not cleaved. {ECO:0000255}.
FT CHAIN 338 758 E2 envelope glycoprotein. {ECO:0000250}.
FT /FTId=PRO_0000238751.
FT CHAIN 759 819 6K protein. {ECO:0000250}.
FT /FTId=PRO_0000238752.
FT CHAIN 820 1258 E1 envelope glycoprotein. {ECO:0000250}.
FT /FTId=PRO_0000238753.
FT TOPO_DOM 338 696 Extracellular. {ECO:0000255}.
FT TRANSMEM 697 717 Helical. {ECO:0000255}.
FT TOPO_DOM 718 758 Cytoplasmic. {ECO:0000255}.
FT TOPO_DOM 759 773 Extracellular. {ECO:0000255}.
FT TRANSMEM 774 794 Helical. {ECO:0000255}.
FT TOPO_DOM 795 796 Cytoplasmic. {ECO:0000255}.
FT TRANSMEM 797 817 Helical. {ECO:0000255}.
FT TOPO_DOM 818 819 Extracellular. {ECO:0000255}.
FT TOPO_DOM 820 1234 Extracellular. {ECO:0000255}.
FT TRANSMEM 1235 1255 Helical. {ECO:0000255}.
FT TOPO_DOM 1256 1258 Cytoplasmic. {ECO:0000255}.
FT DOMAIN 123 271 Peptidase S3. {ECO:0000255|PROSITE-
FT ProRule:PRU01027}.
FT REGION 1 117 Intrinsically disordered, in contact with
FT genomic RNA in nucleocapsid.
FT {ECO:0000255}.
FT REGION 100 110 Ribosome-binding. {ECO:0000250}.
FT REGION 731 751 Transient transmembrane before p62-6K
FT protein processing. {ECO:0000255}.
FT REGION 903 920 E1 fusion peptide loop. {ECO:0000250}.
FT ACT_SITE 149 149 Charge relay system.
FT {ECO:0000255|PROSITE-ProRule:PRU01027}.
FT ACT_SITE 155 155 Charge relay system.
FT {ECO:0000255|PROSITE-ProRule:PRU01027}.
FT ACT_SITE 223 223 Charge relay system.
FT {ECO:0000255|PROSITE-ProRule:PRU01027}.
FT SITE 271 272 Cleavage; by capsid protein.
FT {ECO:0000250}.
FT SITE 337 338 Cleavage; by host furin. {ECO:0000250}.
FT SITE 758 759 Cleavage; by host signal peptidase.
FT {ECO:0000250}.
FT SITE 819 820 Cleavage; by host signal peptidase.
FT {ECO:0000250}.
FT LIPID 731 731 S-palmitoyl cysteine; by host.
FT {ECO:0000250}.
FT LIPID 751 751 S-palmitoyl cysteine; by host.
FT {ECO:0000250}.
FT LIPID 752 752 S-palmitoyl cysteine; by host.
FT {ECO:0000250}.
FT CARBOHYD 283 283 N-linked (GlcNAc...); by host.
FT {ECO:0000255}.
FT DISULFID 868 933 {ECO:0000250}.
FT DISULFID 881 913 {ECO:0000250}.
FT DISULFID 882 915 {ECO:0000250}.
FT DISULFID 887 897 {ECO:0000250}.
FT DISULFID 1078 1090 {ECO:0000250}.
FT DISULFID 1120 1195 {ECO:0000250}.
FT DISULFID 1125 1199 {ECO:0000250}.
FT DISULFID 1147 1189 {ECO:0000250}.
CC --------------------------------------------------------------------------
CC The following FT lines are automated annotations from the MyHits database.
CC --------------------------------------------------------------------------
FT MYHIT 351 752 ipfam:Alpha_E2_glycop [T]
FT MYHIT 279 336 ipfam:Alpha_E3_glycop [T]
FT MYHIT 123 271 iprf:ALPHAVIRUS_CP [T]
FT MYHIT 116 272 ipfam:Peptidase_S3 [T]
FT MYHIT 754 1257 ipfam:Alpha_E1_glycop [T]
SQ SEQUENCE 1258 AA; 138236 MW; 65339C471FB3D31F CRC64;
MNYIPTQTFY GRRWRPRPAA RPWVAPPPVY YPPPPPVPVD PQAQQMQQLI AAVNTLAIRQ
NGTRTPGQQR RKRQPNKPKR KQTPPKKQNP AKTKNKQKPQ PPKPKKRKPG KRERKCMKIE
NDCIFEVKLE GKVTGYACLV GDKVMKPAHV KGVIDNPDLA KLAFKKSSKY DLECAQIPVH
MKSDASQFTH EKPEGHYNWH HGAVQYLNGR FTIPTGAGKP GDSGRPIFDN KGRVVAIVLG
GANEGARTAL SVVTWNKDMV TRITPEGTEE WTALVTTACI LSNLTFDCSL PPCAPCCYEK
DAEGTLRMLE DNVDNPGYYD LLAASTHCDA PQRRRRRGLT EDYKAYKLTK PYIAYCSDCG
NGQFCYSPIA IERVRAEASD GMLKIQISAQ IGLQVDGAHS WTKIRYMKGH DVEDTDRNSL
EVFTTGECTV HGTMGHFIVA TCPEGDSLTV AFVDKHKVRH ACRIAYKHRV PVLGREHFTV
RPHHGVELPC TTYAMRTSVT TEEIEMHVAH DVPDNTFLSK TGNKVKITPK GKSIRYNCTC
GSKESGVTKQ DKEFDNCEVS QCHTMVTAHD KWQFNSPYVP RAGSGKKGKI HVPFPLSNST
CRVPLAPLPN TIPAKNGITL QLHPVAPTLL TYRTLGEKPE HHTEWISESC ERTLPVPEEG
LEYTWGNHAP VRLWAQLTTK GSAHGMPHEI FSYYYGLYPA TTVAVCVGLA CVILLALSAS
CCLCVSARNK CLTPYALTPG AVVPCTLSLL CCAPRAKAAT FAETAAYLWA ENQTVFWMQF
AIPVACFMIV TYCLRHLMLC CRTASFLVAV SLGMGATQAY EHSVTLPNAV GFPYRAHVDR
PGFSPLTLHM EVVSTSLEPT LALDYVTCEY KTVVPSPKVT CCGMSECAHQ QKADFQCKVY
TGVYPFLWGG AYCFCDSENT QLSEAYVERS EVCKHDHAAA YRAHTAALKA KISVTYGSTN
GTAEAFVNGE STARIGDLKM ILGPISTAWS PFDPKIVVYK DEVYNQDYPP YGSGQPGRFG
DLQSRTTESN DVYANTALKL ARPSAGTVHV PYTQTPSGFK YWLKEKGDAL NHKAPFGCII
KTNPVRAENC AVGNIPVSLD IPDAAFTRIV DAPSLTGLKC EVATCTHSSD FGGTLVVEYK
TDKVGTCAVH SESNTAVMQE TSLSVTMDGR GTLHFSTASA SPSFVLKVCS SKTTCTAKCV
PPKDHVVPFP ANHNNVVFPD FSSTAVSWLT HTMGGATVVI AIGITIFLIV TCIAFSRH
//
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