ID   IPRA_SAGSA              Reviewed;         181 AA.
AC   P31608;
DT   01-JUL-1993, integrated into UniProtKB/Swiss-Prot.
DT   01-JUL-1993, sequence version 1.
DT   25-MAY-2022, entry version 70.
DE   RecName: Full=Proteinase inhibitor A;
DE   AltName: Full=Double-headed proteinase inhibitor A;
DE            Short=API-A;
DE   Flags: Precursor;
OS   Sagittaria sagittifolia (Arrowhead).
OC   Eukaryota; Viridiplantae; Streptophyta; Embryophyta; Tracheophyta;
OC   Spermatophyta; Magnoliopsida; Liliopsida; Alismataceae; Sagittaria.
OX   NCBI_TaxID=4451;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RX   PubMed=8468321; DOI=10.1093/oxfordjournals.jbchem.a124019;
RA   Xu W., Tao W., Gong Z., Chi C.-W.;
RT   "cDNA and genomic structures of arrowhead proteinase inhibitors.";
RL   J. Biochem. 113:153-158(1993).
RN   [2]
RP   PROTEIN SEQUENCE OF 25-174.
RX   PubMed=1618743; DOI=10.1093/oxfordjournals.jbchem.a123792;
RA   Yang H.-L., Luo R.-S., Wang L.-X., Zhu D.-X., Chi C.-W.;
RT   "Primary structure and disulfide bridge location of arrowhead double-headed
RT   proteinase inhibitors.";
RL   J. Biochem. 111:537-545(1992).
CC   -!- FUNCTION: Possesses two reactive sites. Inhibits an equimolar amount of
CC       trypsin and chymotrypsin simultaneously, and inhibits kallikrein
CC       weakly.
CC   -!- SUBCELLULAR LOCATION: Secreted.
CC   -!- SIMILARITY: Belongs to the protease inhibitor I3 (leguminous Kunitz-
CC       type inhibitor) family. {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; D13819; BAA02972.1; -; Genomic_DNA.
DR   PIR; A43809; XKARA.
DR   PIR; JX0246; JX0246.
DR   AlphaFoldDB; P31608; -.
DR   SMR; P31608; -.
DR   MEROPS; I03.006; -.
DR   GO; GO:0005576; C:extracellular region; IEA:UniProtKB-SubCell.
DR   GO; GO:0004867; F:serine-type endopeptidase inhibitor activity; IEA:UniProtKB-KW.
DR   InterPro; IPR011065; Kunitz_inhibitor_STI-like_sf.
DR   InterPro; IPR016308; Prot_inh_API-A/B.
DR   InterPro; IPR002160; Prot_inh_Kunz-lg.
DR   PANTHER; PTHR33107; PTHR33107; 2.
DR   Pfam; PF00197; Kunitz_legume; 1.
DR   PIRSF; PIRSF001653; API-B; 1.
DR   SMART; SM00452; STI; 1.
DR   SUPFAM; SSF50386; SSF50386; 1.
PE   1: Evidence at protein level;
KW   Direct protein sequencing; Disulfide bond; Protease inhibitor; Secreted;
KW   Serine protease inhibitor; Signal.
FT   SIGNAL          1..24
FT                   /evidence="ECO:0000269|PubMed:1618743"
FT   CHAIN           25..181
FT                   /note="Proteinase inhibitor A"
FT                   /id="PRO_0000016897"
FT   SITE            68..69
FT                   /note="Reactive bond for trypsin"
FT                   /evidence="ECO:0000305"
FT   SITE            100..101
FT                   /note="Reactive bond"
FT                   /evidence="ECO:0000305"
FT   DISULFID        67..113
FT   DISULFID        134..143
FT   DISULFID        136..139
FT   CONFLICT        61
FT                   /note="T -> W (in Ref. 2; AA sequence)"
FT                   /evidence="ECO:0000305"
FT   CONFLICT        84
FT                   /note="G -> S (in Ref. 2; AA sequence)"
FT                   /evidence="ECO:0000305"
FT   CONFLICT        152
FT                   /note="N -> D (in Ref. 2; AA sequence)"
FT                   /evidence="ECO:0000305"
FT   CONFLICT        166
FT                   /note="V -> I (in Ref. 2; AA sequence)"
FT                   /evidence="ECO:0000305"
FT   CONFLICT        174
FT                   /note="L -> F (in Ref. 2; AA sequence)"
FT                   /evidence="ECO:0000305"
SQ   SEQUENCE   181 AA;  19152 MW;  5E098602BB944A30 CRC64;
     MAASNALLLI SGVLLISLAV LCHGDPVVDS DGDAVQLNLG GNYPLYTIQS AAIGFRGGLS
     TLHKDACKSY VYEAPETDRG LPVGFSASAT SQPVMQLGSR YKFSFSMPVP LICDTAWSIG
     KSTEETGVYK LAACSCEFCK IACPEVGSFN VNGRTLLGIG GEHFTVRFQK FDALAMKTAP
     Q