ID   ISK1_HORSE              Reviewed;          56 AA.
AC   P81634;
DT   15-JUL-1999, integrated into UniProtKB/Swiss-Prot.
DT   15-JUL-1999, sequence version 1.
DT   03-AUG-2022, entry version 96.
DE   RecName: Full=Serine protease inhibitor Kazal-type 1 {ECO:0000250|UniProtKB:P09036};
DE   AltName: Full=Pancreatic secretory trypsin inhibitor {ECO:0000250|UniProtKB:P09036};
GN   Name=SPINK1; Synonyms=PSTI;
OS   Equus caballus (Horse).
OC   Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi; Mammalia;
OC   Eutheria; Laurasiatheria; Perissodactyla; Equidae; Equus.
OX   NCBI_TaxID=9796;
RN   [1]
RP   PROTEIN SEQUENCE.
RC   TISSUE=Pancreas;
RA   Voit J.;
RT   "Representation and characterization of pancreatic secretory proteinase
RT   inhibitors from various animal species.";
RL   Thesis (1993), Ludwig-Maximilians University / Munich, Germany.
CC   -!- FUNCTION: Serine protease inhibitor which exhibits anti-trypsin
CC       activity. In the pancreas, protects against trypsin-catalyzed premature
CC       activation of zymogens. {ECO:0000250|UniProtKB:P09036}.
CC   -!- FUNCTION: In the male reproductive tract, binds to sperm heads where it
CC       modulates sperm capacitance by inhibiting calcium uptake and nitrogen
CC       oxide (NO) production. {ECO:0000250|UniProtKB:P09036}.
CC   -!- SUBCELLULAR LOCATION: Secreted {ECO:0000250|UniProtKB:P09036}.
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DR   AlphaFoldDB; P81634; -.
DR   SMR; P81634; -.
DR   STRING; 9796.ENSECAP00000010304; -.
DR   PaxDb; P81634; -.
DR   HOGENOM; CLU_169765_6_0_1; -.
DR   InParanoid; P81634; -.
DR   OMA; EPSCENF; -.
DR   Proteomes; UP000002281; Unplaced.
DR   GO; GO:0005576; C:extracellular region; IEA:UniProtKB-SubCell.
DR   GO; GO:0004867; F:serine-type endopeptidase inhibitor activity; IEA:UniProtKB-KW.
DR   InterPro; IPR002350; Kazal_dom.
DR   InterPro; IPR036058; Kazal_dom_sf.
DR   InterPro; IPR001239; Prot_inh_Kazal-m.
DR   Pfam; PF00050; Kazal_1; 1.
DR   PRINTS; PR00290; KAZALINHBTR.
DR   SMART; SM00280; KAZAL; 1.
DR   SUPFAM; SSF100895; SSF100895; 1.
DR   PROSITE; PS00282; KAZAL_1; 1.
DR   PROSITE; PS51465; KAZAL_2; 1.
PE   1: Evidence at protein level;
KW   Direct protein sequencing; Disulfide bond; Protease inhibitor;
KW   Reference proteome; Secreted; Serine protease inhibitor.
FT   CHAIN           1..56
FT                   /note="Serine protease inhibitor Kazal-type 1"
FT                   /id="PRO_0000073025"
FT   DOMAIN          3..56
FT                   /note="Kazal-like"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00798"
FT   SITE            18..19
FT                   /note="Reactive bond for trypsin"
FT                   /evidence="ECO:0000250|UniProtKB:P09036,
FT                   ECO:0000255|PROSITE-ProRule:PRU00798"
FT   SITE            20..21
FT                   /note="Necessary for sperm binding"
FT                   /evidence="ECO:0000250|UniProtKB:P09036"
FT   DISULFID        9..38
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00798"
FT   DISULFID        16..35
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00798"
FT   DISULFID        24..56
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00798"
SQ   SEQUENCE   56 AA;  6093 MW;  D0DAA7E4FDB507E0 CRC64;
     DSLGREAKCN NNAGGCTKIY NPVCGTDGNT YPNECMLCVE NQKRQMPVLI QRSGPC