ID   IBBB_PEA                Reviewed;          72 AA.
AC   P56679;
DT   15-JUL-1999, integrated into UniProtKB/Swiss-Prot.
DT   30-MAY-2000, sequence version 2.
DT   25-MAY-2022, entry version 88.
DE   RecName: Full=Seed trypsin/chymotrypsin inhibitor IVB;
DE            Short=PSTI-IVB;
DE   Contains:
DE     RecName: Full=Seed trypsin/chymotrypsin inhibitor II;
DE              Short=PSTI II;
OS   Pisum sativum (Garden pea).
OC   Eukaryota; Viridiplantae; Streptophyta; Embryophyta; Tracheophyta;
OC   Spermatophyta; Magnoliopsida; eudicotyledons; Gunneridae; Pentapetalae;
OC   rosids; fabids; Fabales; Fabaceae; Papilionoideae; 50 kb inversion clade;
OC   NPAAA clade; Hologalegina; IRL clade; Fabeae; Pisum.
OX   NCBI_TaxID=3888;
RN   [1]
RP   PROTEIN SEQUENCE.
RC   STRAIN=cv. Frilene; TISSUE=Seed;
RX   PubMed=9155090; DOI=10.1023/a:1026326808553;
RA   Quillien L., Ferrasson E., Molle D., Gueguen J.;
RT   "Trypsin inhibitor polymorphism: multigene family expression and
RT   posttranslational modification.";
RL   J. Protein Chem. 16:195-203(1997).
RN   [2]
RP   X-RAY CRYSTALLOGRAPHY (2.70 ANGSTROMS), AND DISULFIDE BONDS.
RC   TISSUE=Seed;
RX   PubMed=9887273; DOI=10.1006/jmbi.1998.2351;
RA   Li de la Sierra I., Quillien L., Flecker P., Gueguen J., Brunie S.;
RT   "Dimeric crystal structure of a Bowman-Birk protease inhibitor from pea
RT   seeds.";
RL   J. Mol. Biol. 285:1195-1207(1999).
CC   -!- FUNCTION: Inhibitor of trypsin and of chymotrypsin. May function as a
CC       natural phytochemical defense against predators.
CC   -!- TISSUE SPECIFICITY: Seed.
CC   -!- DEVELOPMENTAL STAGE: During desiccation stage of seed development
CC       increasing activity seems to be associated with appearance of isoform
CC       (PSTI II) which has a stronger affinity for trypsin.
CC   -!- SIMILARITY: Belongs to the Bowman-Birk serine protease inhibitor
CC       family. {ECO:0000305}.
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DR   PDB; 1PBI; X-ray; 2.70 A; A/B=1-72.
DR   PDBsum; 1PBI; -.
DR   AlphaFoldDB; P56679; -.
DR   SMR; P56679; -.
DR   MEROPS; I12.018; -.
DR   EvolutionaryTrace; P56679; -.
DR   GO; GO:0005576; C:extracellular region; IEA:InterPro.
DR   GO; GO:0004867; F:serine-type endopeptidase inhibitor activity; IEA:UniProtKB-KW.
DR   CDD; cd00023; BBI; 1.
DR   Gene3D; 2.10.69.10; -; 1.
DR   InterPro; IPR035995; Bowman-Birk_prot_inh.
DR   InterPro; IPR000877; Prot_inh_BBI.
DR   Pfam; PF00228; Bowman-Birk_leg; 1.
DR   SMART; SM00269; BowB; 1.
DR   SUPFAM; SSF57247; SSF57247; 1.
PE   1: Evidence at protein level;
KW   3D-structure; Direct protein sequencing; Disulfide bond;
KW   Protease inhibitor; Serine protease inhibitor.
FT   CHAIN           1..72
FT                   /note="Seed trypsin/chymotrypsin inhibitor IVB"
FT                   /id="PRO_0000003275"
FT   CHAIN           1..63
FT                   /note="Seed trypsin/chymotrypsin inhibitor II"
FT                   /id="PRO_0000003276"
FT   SITE            16..17
FT                   /note="Reactive bond for trypsin"
FT   SITE            42..43
FT                   /note="Reactive bond for chymotrypsin"
FT   DISULFID        8..61
FT                   /evidence="ECO:0000269|PubMed:9887273,
FT                   ECO:0007744|PDB:1PBI"
FT   DISULFID        9..24
FT                   /evidence="ECO:0000269|PubMed:9887273,
FT                   ECO:0007744|PDB:1PBI"
FT   DISULFID        12..57
FT                   /evidence="ECO:0000269|PubMed:9887273,
FT                   ECO:0007744|PDB:1PBI"
FT   DISULFID        14..22
FT                   /evidence="ECO:0000269|PubMed:9887273,
FT                   ECO:0007744|PDB:1PBI"
FT   DISULFID        31..38
FT                   /evidence="ECO:0000269|PubMed:9887273,
FT                   ECO:0007744|PDB:1PBI"
FT   DISULFID        35..50
FT                   /evidence="ECO:0000269|PubMed:9887273,
FT                   ECO:0007744|PDB:1PBI"
FT   DISULFID        40..48
FT                   /evidence="ECO:0000269|PubMed:9887273,
FT                   ECO:0007744|PDB:1PBI"
FT   STRAND          12..19
FT                   /evidence="ECO:0007829|PDB:1PBI"
FT   STRAND          22..24
FT                   /evidence="ECO:0007829|PDB:1PBI"
FT   STRAND          27..30
FT                   /evidence="ECO:0007829|PDB:1PBI"
FT   STRAND          36..45
FT                   /evidence="ECO:0007829|PDB:1PBI"
FT   STRAND          47..50
FT                   /evidence="ECO:0007829|PDB:1PBI"
FT   STRAND          53..56
FT                   /evidence="ECO:0007829|PDB:1PBI"
FT   STRAND          61..63
FT                   /evidence="ECO:0007829|PDB:1PBI"
FT   STRAND          67..70
FT                   /evidence="ECO:0007829|PDB:1PBI"
SQ   SEQUENCE   72 AA;  7864 MW;  F12E71FAAD9A4BF7 CRC64;
     GDDVKSACCD TCLCTKSNPP TCRCVDVGET CHSACLSCIC AYSNPPKCQC FDTQKFCYKA
     CHNSELEEVI KN