ID   SPI3_VAR67              Reviewed;         373 AA.
AC   P33831;
DT   01-FEB-1994, integrated into UniProtKB/Swiss-Prot.
DT   01-FEB-1994, sequence version 1.
DT   03-AUG-2022, entry version 83.
DE   RecName: Full=Protein K2;
DE   AltName: Full=Serine proteinase inhibitor 3;
DE   Flags: Precursor;
GN   Name=SPI-3; ORFNames=C2L;
OS   Variola virus (isolate Human/India/Ind3/1967) (VARV) (Smallpox virus).
OC   Viruses; Varidnaviria; Bamfordvirae; Nucleocytoviricota; Pokkesviricetes;
OC   Chitovirales; Poxviridae; Chordopoxvirinae; Orthopoxvirus.
OX   NCBI_TaxID=587200;
OH   NCBI_TaxID=9606; Homo sapiens (Human).
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RC   STRAIN=India-1967 / Isolate Ind3;
RX   PubMed=8384129; DOI=10.1016/0014-5793(93)80041-r;
RA   Shchelkunov S.N., Blinov V.M., Sandakhchiev L.S.;
RT   "Genes of variola and vaccinia viruses necessary to overcome the host
RT   protective mechanisms.";
RL   FEBS Lett. 319:80-83(1993).
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}.
CC   ---------------------------------------------------------------------------
CC   Copyrighted by the UniProt Consortium, see https://www.uniprot.org/terms
CC   Distributed under the Creative Commons Attribution (CC BY 4.0) License
CC   ---------------------------------------------------------------------------
DR   EMBL; X69198; CAA48963.1; -; Genomic_DNA.
DR   PIR; B36839; B36839.
DR   RefSeq; NP_042066.1; NC_001611.1.
DR   SMR; P33831; -.
DR   MEROPS; I04.047; -.
DR   GeneID; 1486579; -.
DR   KEGG; vg:1486579; -.
DR   Proteomes; UP000002060; 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   3: Inferred from homology;
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..373
FT                   /note="Protein K2"
FT                   /id="PRO_0000094153"
SQ   SEQUENCE   373 AA;  42660 MW;  6436E09D57471668 CRC64;
     MIVLLILSLA CTAFTYRLQG FTNAGIVAYK NIQDGNEDDN IVFSPFGYSF SMFMSLLPAS
     GNTKVELLKT MDLRKIDLGP AFTELISGLA KPKTSKYTYT DLTYQSFVDN TVCIKPSYYQ
     QYHRFGLYRL NFRRDAVNKI NSIVERRSGM SNVVDSTMLD NNTLWAIINT IYFKGTWQYP
     FDITKTHNTS FTNKYGTKTV PMMSVVTKLQ GNTITIDDEE YDMVRLQYKD ANISMYLAIG
     DNMTHFTDSI MAAKLDYWSS QLGNKVYNLK LPRFSIENKR DIKSIAEMMA PSMFNPDNAS
     FKHMTRDPLY IYKMFQNAKI DVNEQGTVAE ASTIMVATVR SSPEELEFNT PFVFIIRHDI
     TGFILFMGKV ESP