ID   SPI2_SOLTU              Reviewed;         186 AA.
AC   P58515;
DT   23-JAN-2002, integrated into UniProtKB/Swiss-Prot.
DT   23-JAN-2002, sequence version 1.
DT   03-AUG-2022, entry version 83.
DE   RecName: Full=Serine protease inhibitor 2;
DE   AltName: Full=PSPI-21;
DE   AltName: Full=PSPI-21-5.2;
DE   Contains:
DE     RecName: Full=Serine protease inhibitor 2 chain A;
DE   Contains:
DE     RecName: Full=Serine protease inhibitor 2 chain B;
OS   Solanum tuberosum (Potato).
OC   Eukaryota; Viridiplantae; Streptophyta; Embryophyta; Tracheophyta;
OC   Spermatophyta; Magnoliopsida; eudicotyledons; Gunneridae; Pentapetalae;
OC   asterids; lamiids; Solanales; Solanaceae; Solanoideae; Solaneae; Solanum.
OX   NCBI_TaxID=4113;
RN   [1]
RP   PROTEIN SEQUENCE, AND MASS SPECTROMETRY.
RC   STRAIN=cv. Istrinskii;
RX   PubMed=11209756; DOI=10.1515/bc.2000.149;
RA   Valueva T.A., Revina T.A., Mosolov V.V., Mentele R.;
RT   "Primary structure of potato Kunitz-type serine proteinase inhibitor.";
RL   Biol. Chem. 381:1215-1221(2000).
CC   -!- FUNCTION: Potent inhibitor of serine proteases (chymotrypsin and
CC       trypsin). Inhibits tightly human leukocyte elastase (HLE). Does not
CC       inhibit papain, pepsin nor cathepsin D (cysteine and aspartic
CC       proteases). Protects the plant by inhibiting proteases of invading
CC       organisms, decreasing both hyphal growth and zoospores germination of
CC       Phytophthora infestans.
CC   -!- SUBUNIT: Heterodimer of chains A and B; disulfide-linked. Double-headed
CC       inhibitor able to form triple complexes with target proteases, by
CC       binding simultaneously one molecule of trypsin and one molecule of
CC       chymotrypsin.
CC   -!- SUBCELLULAR LOCATION: Vacuole {ECO:0000250}.
CC   -!- TISSUE SPECIFICITY: Tubers.
CC   -!- INDUCTION: By infection with Phytophthora infestans.
CC   -!- PTM: Probably synthesized as a single-chain precursor which is cleaved
CC       to form chain A and chain B.
CC   -!- MASS SPECTROMETRY: [Serine protease inhibitor 2 chain A]: Mass=16396;
CC       Mass_error=16; Method=Electrospray;
CC       Evidence={ECO:0000269|PubMed:11209756};
CC   -!- MASS SPECTROMETRY: [Serine protease inhibitor 2 chain B]: Mass=4182;
CC       Mass_error=4; Method=Electrospray;
CC       Evidence={ECO:0000269|PubMed:11209756};
CC   -!- MISCELLANEOUS: The serine protease inhibitor PSPI-21 comprises two
CC       protein species with pI 5.2 and 6.3, denoted as PSPI-21-5.2 and PSPI-
CC       21-6.3. They may be encoded by two alleles at the same gene locus.
CC   -!- SIMILARITY: Belongs to the protease inhibitor I3 (leguminous Kunitz-
CC       type inhibitor) family. {ECO:0000305}.
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DR   AlphaFoldDB; P58515; -.
DR   SMR; P58515; -.
DR   MEROPS; I03.020; -.
DR   PRIDE; P58515; -.
DR   Proteomes; UP000011115; Unassembled WGS sequence.
DR   ExpressionAtlas; P58515; baseline.
DR   GO; GO:0005773; C:vacuole; IEA:UniProtKB-SubCell.
DR   GO; GO:0004867; F:serine-type endopeptidase inhibitor activity; IEA:UniProtKB-KW.
DR   CDD; cd00178; STI; 1.
DR   InterPro; IPR011065; Kunitz_inhibitor_STI-like_sf.
DR   InterPro; IPR002160; Prot_inh_Kunz-lg.
DR   PANTHER; PTHR33107; PTHR33107; 1.
DR   Pfam; PF00197; Kunitz_legume; 1.
DR   PRINTS; PR00291; KUNITZINHBTR.
DR   SMART; SM00452; STI; 1.
DR   SUPFAM; SSF50386; SSF50386; 1.
DR   PROSITE; PS00283; SOYBEAN_KUNITZ; 1.
PE   1: Evidence at protein level;
KW   Direct protein sequencing; Disulfide bond; Protease inhibitor;
KW   Reference proteome; Serine protease inhibitor; Vacuole.
FT   CHAIN           1..150
FT                   /note="Serine protease inhibitor 2 chain A"
FT                   /id="PRO_0000016901"
FT   CHAIN           151..186
FT                   /note="Serine protease inhibitor 2 chain B"
FT                   /id="PRO_0000016902"
FT   SITE            67..68
FT                   /note="Reactive bond for trypsin"
FT   SITE            115..116
FT                   /note="Reactive bond for chymotrypsin or HLE"
FT   DISULFID        48..97
FT                   /evidence="ECO:0000250"
FT   DISULFID        146..157
FT                   /note="Interchain (between A and B chains)"
FT                   /evidence="ECO:0000250"
FT   NON_CONS        150..151
FT                   /evidence="ECO:0000305"
SQ   SEQUENCE   186 AA;  20116 MW;  26C19E0BB8A01E26 CRC64;
     LPSDATPVLD VTGKELDSRL SYRIISTFWG ALGGDVYLGK SPNSDAPCAN GIFRYNSDVG
     PSGTPVRFIG SSSHFGQGIF ENELLNIQFA ISTSKLCVSY TIWKVGDYDA SLGTMLLETG
     GTIGQADSSW FKIVKSSQLG YNLLYCPVTS SSDDQFCSKV GVVHQNGKRR LALVNENPLD
     VLFQEV