ID   ISK1_CANLF              Reviewed;          57 AA.
AC   P04542;
DT   13-AUG-1987, integrated into UniProtKB/Swiss-Prot.
DT   13-AUG-1987, sequence version 1.
DT   03-AUG-2022, entry version 121.
DE   RecName: Full=Serine protease inhibitor Kazal-type 1 {ECO:0000250|UniProtKB:P09036};
DE   AltName: Full=Pancreatic secretory trypsin inhibitor {ECO:0000303|PubMed:4054311};
GN   Name=SPINK1; Synonyms=PSTI;
OS   Canis lupus familiaris (Dog) (Canis familiaris).
OC   Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi; Mammalia;
OC   Eutheria; Laurasiatheria; Carnivora; Caniformia; Canidae; Canis.
OX   NCBI_TaxID=9615;
RN   [1]
RP   PROTEIN SEQUENCE, FUNCTION, AND SUBCELLULAR LOCATION.
RX   PubMed=4054311; DOI=10.1016/0014-5793(85)80022-3;
RA   Kikuchi N., Nagata K., Yoshida N., Tanaka T., Yamamoto M., Saitoh Y.;
RT   "Purification and complete amino acid sequence of canine pancreatic
RT   secretory trypsin inhibitor.";
RL   FEBS Lett. 191:269-272(1985).
CC   -!- FUNCTION: Serine protease inhibitor which exhibits anti-trypsin
CC       activity (PubMed:4054311). In the pancreas, protects against trypsin-
CC       catalyzed premature activation of zymogens (By similarity).
CC       {ECO:0000250|UniProtKB:P09036, ECO:0000269|PubMed:4054311}.
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:0000269|PubMed:4054311}.
CC   -!- MISCELLANEOUS: This protein is unusual, with respect to the other
CC       mammalian SPINK1 proteins, in having an extra N-terminal residue.
CC   ---------------------------------------------------------------------------
CC   Copyrighted by the UniProt Consortium, see https://www.uniprot.org/terms
CC   Distributed under the Creative Commons Attribution (CC BY 4.0) License
CC   ---------------------------------------------------------------------------
DR   PIR; A01232; TIDGA.
DR   AlphaFoldDB; P04542; -.
DR   SMR; P04542; -.
DR   STRING; 9615.ENSCAFP00000009934; -.
DR   PaxDb; P04542; -.
DR   eggNOG; KOG3649; Eukaryota.
DR   HOGENOM; CLU_169765_6_0_1; -.
DR   InParanoid; P04542; -.
DR   OMA; EPSCENF; -.
DR   Proteomes; UP000002254; 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..57
FT                   /note="Serine protease inhibitor Kazal-type 1"
FT                   /id="PRO_0000073024"
FT   DOMAIN          4..57
FT                   /note="Kazal-like"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00798"
FT   SITE            19..20
FT                   /note="Reactive bond for trypsin"
FT                   /evidence="ECO:0000250|UniProtKB:P09036,
FT                   ECO:0000255|PROSITE-ProRule:PRU00798"
FT   SITE            21..22
FT                   /note="Necessary for sperm binding"
FT                   /evidence="ECO:0000250|UniProtKB:P09036"
FT   DISULFID        10..39
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00798"
FT   DISULFID        17..36
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00798"
FT   DISULFID        25..57
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00798"
SQ   SEQUENCE   57 AA;  6319 MW;  2DE674A2FD98CD43 CRC64;
     NNMLQRQANC NLKVNGCNKI YNPICGSDGI TYANECLLCL ENKKRQTSIL VEKSGPC