ID   SPI3_VACCC              Reviewed;         369 AA.
AC   P20532;
DT   01-FEB-1991, integrated into UniProtKB/Swiss-Prot.
DT   01-FEB-1991, sequence version 1.
DT   23-FEB-2022, entry version 81.
DE   RecName: Full=Protein K2;
DE   AltName: Full=Serine proteinase inhibitor 3;
DE   Flags: Precursor;
GN   Name=SPI-3; ORFNames=K2L;
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).
RN   [3]
RP   INTERACTION WITH A56, AND SUBCELLULAR LOCATION.
RX   PubMed=21715594; DOI=10.1099/vir.0.030460-0;
RA   Dehaven B.C., Gupta K., Isaacs S.N.;
RT   "The vaccinia virus A56 protein: a multifunctional transmembrane
RT   glycoprotein that anchors two secreted viral proteins.";
RL   J. Gen. Virol. 92:1971-1980(2011).
CC   -!- FUNCTION: Prevents cell to cell fusion via its interaction with A56
CC       protein. The A56-K2 complex associates with components of the entry
CC       fusion complex (EFC) presumably to avoid superinfection and syncytium
CC       formation (By similarity). {ECO:0000250}.
CC   -!- SUBUNIT: Interacts with A56 protein. {ECO:0000250}.
CC   -!- SUBCELLULAR LOCATION: Virion membrane {ECO:0000250}; Peripheral
CC       membrane protein {ECO:0000250}. Host cell membrane {ECO:0000250};
CC       Peripheral membrane protein {ECO:0000250}; Extracellular side
CC       {ECO:0000250}. Note=Component of extracellular enveloped virus (EEV)
CC       but not intracellular mature virus (IMV). Anchored to the surface of
CC       the outermost membrane of EEV via its interaction with A56 protein (By
CC       similarity). {ECO:0000250}.
CC   -!- SIMILARITY: Belongs to the serpin family. Poxviruses subfamily.
CC       {ECO:0000305}.
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DR   EMBL; M35027; AAA48006.1; -; Genomic_DNA.
DR   PIR; A42505; WMVZ1E.
DR   SMR; P20532; -.
DR   MEROPS; I04.047; -.
DR   Proteomes; UP000008269; Genome.
DR   GO; GO:0005615; C:extracellular space; IEA:InterPro.
DR   GO; GO:0020002; C:host cell plasma membrane; IEA:UniProtKB-SubCell.
DR   GO; GO:0016020; C:membrane; IEA:UniProtKB-KW.
DR   GO; GO:0055036; C:virion membrane; IEA:UniProtKB-SubCell.
DR   GO; GO:0004867; F:serine-type endopeptidase inhibitor activity; IEA:UniProtKB-KW.
DR   Gene3D; 2.30.39.10; -; 1.
DR   Gene3D; 3.30.497.10; -; 1.
DR   InterPro; IPR023796; Serpin_dom.
DR   InterPro; IPR000215; Serpin_fam.
DR   InterPro; IPR036186; Serpin_sf.
DR   InterPro; IPR042178; Serpin_sf_1.
DR   InterPro; IPR042185; Serpin_sf_2.
DR   PANTHER; PTHR11461; PTHR11461; 1.
DR   Pfam; PF00079; Serpin; 1.
DR   SMART; SM00093; SERPIN; 1.
DR   SUPFAM; SSF56574; SSF56574; 1.
PE   1: Evidence at protein level;
KW   Host cell membrane; Host membrane; Membrane; Protease inhibitor;
KW   Reference proteome; Serine protease inhibitor; Signal; Virion.
FT   SIGNAL          1..15
FT                   /evidence="ECO:0000255"
FT   CHAIN           16..369
FT                   /note="Protein K2"
FT                   /id="PRO_0000094151"
SQ   SEQUENCE   369 AA;  42300 MW;  D6F8CB2E914925FE CRC64;
     MIALLILSLT CSVSTYRLQG FTNAGIVAYK NIQDDNIVFS PFGYSFSMFM SLLPASGNTR
     IELLKTMDLR KRDLGPAFTE LISGLAKLKT SKYTYTDLTY QSFVDNTVCI KPLYYQQYHR
     FGLYRLNFRR DAVNKINSIV ERRSGMSNVV DSNMLDNNTL WAIINTIYFK GTWQYPFDIT
     KTRNASFTNK YGTKTVPMMN VVTKLQGNTI TIDDEEYDMV RLPYKDANIS MYLAIGDNMT
     HFTDSITAAK LDYWSFQLGN KVYNLKLPKF SIENKRDIKS IAEMMAPSMF NPDNASFKHM
     TRDPLYIYKM FQNAKIDVDE QGTVAEASTI MVATARSSPE KLEFNTPFVF IIRHDITGFI
     LFMGKVESP