ID   ITR3_SPIOL              Reviewed;          37 AA.
AC   P84781;
DT   26-JUN-2007, integrated into UniProtKB/Swiss-Prot.
DT   26-JUN-2007, sequence version 1.
DT   25-MAY-2022, entry version 25.
DE   RecName: Full=Trypsin inhibitor 3;
DE   AltName: Full=SOTI III;
DE   AltName: Full=Trypsin inhibitor III;
OS   Spinacia oleracea (Spinach).
OC   Eukaryota; Viridiplantae; Streptophyta; Embryophyta; Tracheophyta;
OC   Spermatophyta; Magnoliopsida; eudicotyledons; Gunneridae; Pentapetalae;
OC   Caryophyllales; Chenopodiaceae; Chenopodioideae; Anserineae; Spinacia.
OX   NCBI_TaxID=3562;
RN   [1] {ECO:0000305}
RP   PROTEIN SEQUENCE, FUNCTION, AND MASS SPECTROMETRY.
RC   TISSUE=Seed {ECO:0000269|PubMed:17481678};
RX   PubMed=17481678; DOI=10.1016/j.phytochem.2007.03.012;
RA   Kowalska J., Pszczola K., Wilimowska-Pelc A., Lorenc-Kubis I., Zuziak E.,
RA   Lugowski M., Legowska A., Kwiatkowska A., Sleszynska M., Lesner A.,
RA   Walewska A., Zablotna E., Rolka K., Wilusz T.;
RT   "Trypsin inhibitors from the garden four o'clock (Mirabilis jalapa) and
RT   spinach (Spinacia oleracea) seeds: isolation, characterization and chemical
RT   synthesis.";
RL   Phytochemistry 68:1487-1496(2007).
CC   -!- FUNCTION: Trypsin inhibitor. {ECO:0000269|PubMed:17481678}.
CC   -!- DOMAIN: The presence of a 'disulfide through disulfide knot'
CC       structurally defines this protein as a knottin. {ECO:0000250}.
CC   -!- MASS SPECTROMETRY: Mass=3838.4; Method=Electrospray;
CC       Evidence={ECO:0000269|PubMed:17481678};
CC   -!- SIMILARITY: Belongs to the Mirabilis serine proteinase inhibitor
CC       family. {ECO:0000269|PubMed:17481678}.
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DR   PDB; 4AOQ; X-ray; 2.00 A; D/E/F=1-37.
DR   PDB; 4AOR; X-ray; 1.70 A; D/E/F=1-37.
DR   PDBsum; 4AOQ; -.
DR   PDBsum; 4AOR; -.
DR   AlphaFoldDB; P84781; -.
DR   SMR; P84781; -.
DR   MEROPS; I90.002; -.
DR   GO; GO:0004867; F:serine-type endopeptidase inhibitor activity; IEA:UniProtKB-KW.
DR   InterPro; IPR040875; Tryp_inh.
DR   Pfam; PF17983; Tryp_inh; 1.
PE   1: Evidence at protein level;
KW   3D-structure; Direct protein sequencing; Disulfide bond; Knottin;
KW   Protease inhibitor; Serine protease inhibitor.
FT   PEPTIDE         1..37
FT                   /note="Trypsin inhibitor 3"
FT                   /id="PRO_0000292939"
FT   SITE            32..33
FT                   /note="Reactive bond for trypsin"
FT                   /evidence="ECO:0000250|UniProtKB:P84779"
FT   DISULFID        4..21
FT                   /evidence="ECO:0000250|UniProtKB:P84779"
FT   DISULFID        11..25
FT                   /evidence="ECO:0000250|UniProtKB:P84779"
FT   DISULFID        20..36
FT                   /evidence="ECO:0000250|UniProtKB:P84779"
FT   STRAND          9..11
FT                   /evidence="ECO:0007829|PDB:4AOQ"
FT   HELIX           17..19
FT                   /evidence="ECO:0007829|PDB:4AOR"
FT   STRAND          25..27
FT                   /evidence="ECO:0007829|PDB:4AOR"
FT   STRAND          29..36
FT                   /evidence="ECO:0007829|PDB:4AOR"
SQ   SEQUENCE   37 AA;  3837 MW;  D1F1F78D4EF22274 CRC64;
     EDKCSPSGAI CSGFGPPEQC CSGACVPHPI LRIFVCQ