ID   ITR2_SECED              Reviewed;          32 AA.
AC   P84451; P84453;
DT   01-MAR-2005, integrated into UniProtKB/Swiss-Prot.
DT   01-MAR-2005, sequence version 1.
DT   25-MAY-2022, entry version 53.
DE   RecName: Full=Trypsin inhibitor 2b;
DE   AltName: Full=SETI-IIb;
DE   AltName: Full=Trypsin inhibitor IIb;
DE   Contains:
DE     RecName: Full=Trypsin inhibitor 2a;
DE     AltName: Full=SETI-IIa;
DE     AltName: Full=Trypsin inhibitor IIa;
OS   Sechium edule (Chayote) (Sicyos edulis).
OC   Eukaryota; Viridiplantae; Streptophyta; Embryophyta; Tracheophyta;
OC   Spermatophyta; Magnoliopsida; eudicotyledons; Gunneridae; Pentapetalae;
OC   rosids; fabids; Cucurbitales; Cucurbitaceae; Sicyoeae; Sicyos.
OX   NCBI_TaxID=184140;
RN   [1]
RP   PROTEIN SEQUENCE, FUNCTION, AND MASS SPECTROMETRY.
RC   TISSUE=Seed;
RX   PubMed=16406091; DOI=10.1016/j.phytochem.2005.11.016;
RA   Laure H.J., Faca V.M., Lzumi C., Padovan J.C., Greene L.J.;
RT   "Low molecular weight squash trypsin inhibitors from Sechium edule seeds.";
RL   Phytochemistry 67:362-370(2006).
CC   -!- FUNCTION: Inhibits trypsin. {ECO:0000269|PubMed:16406091}.
CC   -!- SUBCELLULAR LOCATION: Secreted.
CC   -!- DOMAIN: The presence of a 'disulfide through disulfide knot'
CC       structurally defines this protein as a knottin. {ECO:0000250}.
CC   -!- MASS SPECTROMETRY: [Trypsin inhibitor 2a]: Mass=3535.1; Mass_error=0.1;
CC       Method=MALDI; Evidence={ECO:0000269|PubMed:16406091};
CC   -!- MASS SPECTROMETRY: [Trypsin inhibitor 2b]: Mass=3664.3; Mass_error=0.1;
CC       Method=MALDI; Evidence={ECO:0000269|PubMed:16406091};
CC   -!- SIMILARITY: Belongs to the protease inhibitor I7 (squash-type serine
CC       protease inhibitor) family. {ECO:0000305}.
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DR   AlphaFoldDB; P84451; -.
DR   SMR; P84451; -.
DR   GO; GO:0005576; C:extracellular region; IEA:UniProtKB-SubCell.
DR   GO; GO:0004867; F:serine-type endopeptidase inhibitor activity; IEA:UniProtKB-KW.
DR   CDD; cd00150; PlantTI; 1.
DR   InterPro; IPR000737; Prot_inh_squash.
DR   InterPro; IPR011052; Proteinase_amylase_inhib_sf.
DR   Pfam; PF00299; Squash; 1.
DR   PRINTS; PR00293; SQUASHINHBTR.
DR   SUPFAM; SSF57027; SSF57027; 1.
DR   PROSITE; PS00286; SQUASH_INHIBITOR; 1.
PE   1: Evidence at protein level;
KW   Direct protein sequencing; Disulfide bond; Knottin; Protease inhibitor;
KW   Secreted; Serine protease inhibitor.
FT   PEPTIDE         1..32
FT                   /note="Trypsin inhibitor 2b"
FT                   /id="PRO_0000033216"
FT   PEPTIDE         2..32
FT                   /note="Trypsin inhibitor 2a"
FT                   /id="PRO_0000033217"
FT   SITE            8..9
FT                   /note="Reactive bond"
FT   DISULFID        6..23
FT                   /evidence="ECO:0000250"
FT   DISULFID        13..25
FT                   /evidence="ECO:0000250"
FT   DISULFID        19..31
FT                   /evidence="ECO:0000250"
SQ   SEQUENCE   32 AA;  3670 MW;  BAF5D27A673884FE CRC64;
     EEDRKCPKIL MRCKRDSDCL AKCTCQESGY CG