ID   ISK1_SHEEP              Reviewed;          56 AA.
AC   P00997;
DT   21-JUL-1986, integrated into UniProtKB/Swiss-Prot.
DT   21-JUL-1986, sequence version 1.
DT   25-MAY-2022, entry version 89.
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   Ovis aries (Sheep).
OC   Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi; Mammalia;
OC   Eutheria; Laurasiatheria; Artiodactyla; Ruminantia; Pecora; Bovidae;
OC   Caprinae; Ovis.
OX   NCBI_TaxID=9940;
RN   [1]
RP   PARTIAL PROTEIN SEQUENCE.
RA   Tschesche H., Wachter E., Kupfer S., Obermeier R., Reidel G., Haenisch G.,
RA   Schneider M.;
RL   (In) Fritz H., Tschesche H. (eds.);
RL   Proceedings of the international research conference on proteinase
RL   inhibitors, pp.207-222, Walter de Gruyter, New York (1971).
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   PIR; A94487; TISHA.
DR   AlphaFoldDB; P00997; -.
DR   SMR; P00997; -.
DR   STRING; 9940.ENSOARP00000004038; -.
DR   MEROPS; I01.011; -.
DR   eggNOG; KOG3649; Eukaryota.
DR   Proteomes; UP000002356; 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_0000073028"
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;  6145 MW;  B8459712AC851B26 CRC64;
     NILGREAKCT NEVNGCPRIY NPVCGTDGVT YANECLLCME NKERQTPVLI QKSGPC