ID   IBBB4_HYAOR             Reviewed;          57 AA.
AC   C0HLT0;
DT   02-JUN-2021, integrated into UniProtKB/Swiss-Prot.
DT   02-JUN-2021, sequence version 1.
DT   03-AUG-2022, entry version 5.
DE   RecName: Full=Bowman-Birk type proteinase inhibitor B4 {ECO:0000303|PubMed:33666645};
DE            Short=HOSPI-B4 {ECO:0000303|PubMed:33666645};
OS   Hyacinthus orientalis (Common hyacinth).
OC   Eukaryota; Viridiplantae; Streptophyta; Embryophyta; Tracheophyta;
OC   Spermatophyta; Magnoliopsida; Liliopsida; Asparagales; Hyacinthaceae;
OC   Hyacinthoideae; Hyacintheae; Hyacinthus.
OX   NCBI_TaxID=82025;
RN   [1]
RP   PROTEIN SEQUENCE, FUNCTION, AND TISSUE SPECIFICITY.
RC   TISSUE=Bulb {ECO:0000303|PubMed:33666645};
RX   PubMed=33666645; DOI=10.1042/bcj20201005;
RA   Aoki-Shioi N., Terada S., Hellinger R., Furuta Y., Gruber C.W.;
RT   "Isolation and functional diversity of Bowman-Birk type serine proteinase
RT   inhibitors from Hyacinthus orientalis.";
RL   Biochem. J. 478:1287-1301(2021).
CC   -!- FUNCTION: Serine protease inhibitor (PubMed:33666645). Inhibits trypsin
CC       (Ki = 110 nM) and very weakly inhibits chymotrypsin (Ki =1200 nM)
CC       (PubMed:33666645). Does not inhibit bacterial subtilisin
CC       (PubMed:33666645). {ECO:0000269|PubMed:33666645}.
CC   -!- TISSUE SPECIFICITY: Expressed in bulb (at protein level).
CC       {ECO:0000269|PubMed:33666645}.
CC   -!- SIMILARITY: Belongs to the Bowman-Birk serine protease inhibitor
CC       family. {ECO:0000305}.
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DR   AlphaFoldDB; C0HLT0; -.
DR   SMR; C0HLT0; -.
DR   GO; GO:0005576; C:extracellular region; IEA:InterPro.
DR   GO; GO:0004867; F:serine-type endopeptidase inhibitor activity; IDA:UniProtKB.
DR   GO; GO:0010951; P:negative regulation of endopeptidase activity; IDA:UniProtKB.
DR   Gene3D; 2.10.69.10; -; 1.
DR   InterPro; IPR035995; Bowman-Birk_prot_inh.
PE   1: Evidence at protein level;
KW   Direct protein sequencing; Disulfide bond; Protease inhibitor;
KW   Serine protease inhibitor.
FT   CHAIN           1..57
FT                   /note="Bowman-Birk type proteinase inhibitor B4"
FT                   /id="PRO_0000452980"
FT   SITE            14..15
FT                   /note="Reactive bond for trypsin"
FT                   /evidence="ECO:0000250|UniProtKB:P80321"
FT   DISULFID        6..55
FT                   /evidence="ECO:0000250|UniProtKB:P80321"
FT   DISULFID        12..17
FT                   /evidence="ECO:0000250|UniProtKB:P80321"
FT   DISULFID        26..33
FT                   /evidence="ECO:0000250|UniProtKB:P80321"
FT   DISULFID        30..47
FT                   /evidence="ECO:0000250|UniProtKB:P80321"
SQ   SEQUENCE   57 AA;  6321 MW;  A3290C0D26E6D107 CRC64;
     GQQPLCNDCF ACARSLCICG DLVPQCHEGC QQCEKVDTLS GKPLYQCRSF EDYQCAN