ID   A21_VACCC               Reviewed;         117 AA.
AC   P20996;
DT   01-FEB-1991, integrated into UniProtKB/Swiss-Prot.
DT   01-FEB-1991, sequence version 1.
DT   25-MAY-2022, entry version 76.
DE   RecName: Full=Virion membrane protein A21;
GN   ORFNames=A21L;
OS   Vaccinia virus (strain Copenhagen) (VACV).
OC   Viruses; Varidnaviria; Bamfordvirae; Nucleocytoviricota; Pokkesviricetes;
OC   Chitovirales; Poxviridae; Chordopoxvirinae; Orthopoxvirus; Vaccinia virus.
OX   NCBI_TaxID=10249;
OH   NCBI_TaxID=9606; Homo sapiens (Human).
RN   [1]
RP   NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
RX   PubMed=2219722; DOI=10.1016/0042-6822(90)90294-2;
RA   Goebel S.J., Johnson G.P., Perkus M.E., Davis S.W., Winslow J.P.,
RA   Paoletti E.;
RT   "The complete DNA sequence of vaccinia virus.";
RL   Virology 179:247-266(1990).
RN   [2]
RP   NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
RA   Goebel S.J., Johnson G.P., Perkus M.E., Davis S.W., Winslow J.P.,
RA   Paoletti E.;
RT   "Appendix to 'The complete DNA sequence of vaccinia virus'.";
RL   Virology 179:517-563(1990).
CC   -!- FUNCTION: Envelope protein part of the entry-fusion complex responsible
CC       for the virus membrane fusion with host cell membrane during virus
CC       entry. {ECO:0000250}.
CC   -!- SUBUNIT: Envelope protein part of a stable entry-fusion complex (EFC)
CC       which is at least composed of proteins A16, A21, A28, G3, G9, H2, J5,
CC       and L5. Formation of the viral membrane is necessary for the assembly
CC       of the complex (By similarity). {ECO:0000250}.
CC   -!- SUBCELLULAR LOCATION: Virion membrane {ECO:0000305}; Single-pass type
CC       III membrane protein {ECO:0000305}. Note=Component of the mature virion
CC       (MV) membrane. The mature virion is located in the cytoplasm of
CC       infected cells and is probably released by cell lysis (By similarity).
CC       {ECO:0000250}.
CC   -!- PTM: Contains two intramolecular disulfide bonds. They are created by
CC       the viral disulfide bond formation pathway, a poxvirus-specific pathway
CC       that operates on the cytoplasmic side of the MV membranes (By
CC       similarity). {ECO:0000250}.
CC   -!- SIMILARITY: Belongs to the chordopoxvirinae A21 family. {ECO:0000305}.
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DR   EMBL; M35027; AAA48142.1; -; Genomic_DNA.
DR   PIR; E42519; E42519.
DR   SMR; P20996; -.
DR   DIP; DIP-2188N; -.
DR   IntAct; P20996; 1.
DR   MINT; P20996; -.
DR   Proteomes; UP000008269; Genome.
DR   GO; GO:0016021; C:integral component of membrane; IEA:UniProtKB-KW.
DR   GO; GO:0019031; C:viral envelope; IEA:UniProtKB-KW.
DR   GO; GO:0055036; C:virion membrane; IEA:UniProtKB-SubCell.
DR   GO; GO:0039663; P:membrane fusion involved in viral entry into host cell; IEA:UniProtKB-KW.
DR   GO; GO:0046718; P:viral entry into host cell; IEA:UniProtKB-KW.
DR   InterPro; IPR007987; Poxvirus_A21.
DR   Pfam; PF05323; Pox_A21; 1.
PE   3: Inferred from homology;
KW   Disulfide bond; Fusion of virus membrane with host membrane; Membrane;
KW   Reference proteome; Signal-anchor; Transmembrane; Transmembrane helix;
KW   Viral envelope protein; Viral penetration into host cytoplasm; Virion;
KW   Virus entry into host cell.
FT   CHAIN           1..117
FT                   /note="Virion membrane protein A21"
FT                   /id="PRO_0000099271"
FT   TRANSMEM        1..21
FT                   /note="Helical; Signal-anchor for type III membrane
FT                   protein"
FT                   /evidence="ECO:0000255"
FT   TOPO_DOM        22..117
FT                   /note="Virion surface"
FT                   /evidence="ECO:0000255"
SQ   SEQUENCE   117 AA;  13645 MW;  D8629B6D437D49A6 CRC64;
     MITLFLILCY FILIFNIIVP AISEKMRRER AAYVNYKRLN KNFICVDDRL FSYNFTTSGI
     KAKVAVDNKN VPIPCSKINE VNNNKDVDTL YCDKDRDDIP GFARSCYRAY SDLFFTT