ID   CSTI_BOMMO              Reviewed;          55 AA.
AC   P81902;
DT   13-DEC-2002, integrated into UniProtKB/Swiss-Prot.
DT   01-JUN-2001, sequence version 1.
DT   25-MAY-2022, entry version 73.
DE   RecName: Full=Trypsin inhibitor;
DE   AltName: Full=Cocoon shell-associated trypsin inhibitor;
DE            Short=CSTI;
OS   Bombyx mori (Silk moth).
OC   Eukaryota; Metazoa; Ecdysozoa; Arthropoda; Hexapoda; Insecta; Pterygota;
OC   Neoptera; Endopterygota; Lepidoptera; Glossata; Ditrysia; Bombycoidea;
OC   Bombycidae; Bombycinae; Bombyx.
OX   NCBI_TaxID=7091 {ECO:0000305};
RN   [1] {ECO:0000305}
RP   PROTEIN SEQUENCE, CHARACTERIZATION, AND MASS SPECTROMETRY.
RC   STRAIN=Asahi;
RX   PubMed=9914483; DOI=10.1046/j.1432-1327.1999.00030.x;
RA   Kurioka A., Yamazaki M., Hirano H.;
RT   "Primary structure and possible functions of a trypsin inhibitor of Bombyx
RT   mori.";
RL   Eur. J. Biochem. 259:120-126(1999).
CC   -!- FUNCTION: This cocoon shell-associated protein inhibits trypsin
CC       Activity by forming a low-dissociation complex with trypsin. May play
CC       an important part in regulating proteolytic activity in the silk gland
CC       or protecting silk proteins from degradation during histolysis.
CC   -!- SUBUNIT: Monomer.
CC   -!- TISSUE SPECIFICITY: Expressed exclusively in the middle silk gland.
CC   -!- DEVELOPMENTAL STAGE: Expression differentially regulated in the middle
CC       silk glands during the final stage of larval growth with highest
CC       expression before the onset of spinning.
CC   -!- MASS SPECTROMETRY: Mass=6658; Method=Electrospray;
CC       Evidence={ECO:0000269|PubMed:9914483};
CC   -!- MISCELLANEOUS: Has an isoelectric point of 4.3.
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DR   AlphaFoldDB; P81902; -.
DR   SMR; P81902; -.
DR   Proteomes; UP000005204; Unassembled WGS sequence.
DR   GO; GO:0004867; F:serine-type endopeptidase inhibitor activity; IEA:UniProtKB-KW.
DR   CDD; cd00109; KU; 1.
DR   Gene3D; 4.10.410.10; -; 1.
DR   InterPro; IPR002223; Kunitz_BPTI.
DR   InterPro; IPR036880; Kunitz_BPTI_sf.
DR   InterPro; IPR020901; Prtase_inh_Kunz-CS.
DR   Pfam; PF00014; Kunitz_BPTI; 1.
DR   PRINTS; PR00759; BASICPTASE.
DR   SMART; SM00131; KU; 1.
DR   SUPFAM; SSF57362; SSF57362; 1.
DR   PROSITE; PS00280; BPTI_KUNITZ_1; 1.
DR   PROSITE; PS50279; BPTI_KUNITZ_2; 1.
PE   1: Evidence at protein level;
KW   Developmental protein; Direct protein sequencing; Disulfide bond;
KW   Protease inhibitor; Reference proteome; Serine protease inhibitor.
FT   CHAIN           1..55
FT                   /note="Trypsin inhibitor"
FT                   /id="PRO_0000155424"
FT   DOMAIN          4..54
FT                   /note="BPTI/Kunitz inhibitor"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00031"
FT   SITE            14..15
FT                   /note="Reactive bond for trypsin"
FT                   /evidence="ECO:0000250"
FT   DISULFID        4..54
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00031"
FT   DISULFID        13..37
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00031"
FT   DISULFID        29..50
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00031"
SQ   SEQUENCE   55 AA;  6027 MW;  C2739BB8F2BB6E59 CRC64;
     NPDCLLPIKT GPCKGSFPRY AYDSSEDKCV EFIYGGCQAN ANNFETIEEC EAACL