ID   ITRP_HALRO              Reviewed;          55 AA.
AC   P16589;
DT   01-AUG-1990, integrated into UniProtKB/Swiss-Prot.
DT   01-AUG-1990, sequence version 1.
DT   25-MAY-2022, entry version 80.
DE   RecName: Full=Trypsin inhibitor;
DE   AltName: Full=ATI;
OS   Halocynthia roretzi (Sea squirt) (Cynthia roretzi).
OC   Eukaryota; Metazoa; Chordata; Tunicata; Ascidiacea; Stolidobranchia;
OC   Pyuridae; Halocynthia.
OX   NCBI_TaxID=7729;
RN   [1]
RP   PROTEIN SEQUENCE.
RC   TISSUE=Hemolymph;
RX   PubMed=2341375; DOI=10.1093/oxfordjournals.jbchem.a123058;
RA   Kumazaki T., Hoshiba N., Yokosawa H., Ishii S.;
RT   "Primary structure of ascidian trypsin inhibitors in the hemolymph of a
RT   solitary ascidian, Halocynthia roretzi.";
RL   J. Biochem. 107:409-413(1990).
RN   [2]
RP   DISULFIDE BONDS.
RX   PubMed=2111316; DOI=10.1093/oxfordjournals.jbchem.a123059;
RA   Kumazaki T., Ishii S.;
RT   "Disulfide bridge structure of ascidian trypsin inhibitor I: similarity to
RT   Kazal-type inhibitors.";
RL   J. Biochem. 107:414-419(1990).
RN   [3]
RP   STRUCTURE BY NMR.
RX   PubMed=12186551; DOI=10.1021/bi026035o;
RA   Hemmi H., Yoshida T., Kumazaki T., Nemoto N., Hasegawa J., Nishioka F.,
RA   Kyogoku Y., Yokosawa H., Kobayashi Y.;
RT   "Solution structure of ascidian trypsin inhibitor determined by nuclear
RT   magnetic resonance spectroscopy.";
RL   Biochemistry 41:10657-10664(2002).
CC   -!- FUNCTION: Potent inhibitor of trypsin.
CC   -!- SUBCELLULAR LOCATION: Secreted.
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DR   PDB; 1IW4; NMR; -; A=1-55.
DR   PDBsum; 1IW4; -.
DR   AlphaFoldDB; P16589; -.
DR   SMR; P16589; -.
DR   MEROPS; I05.001; -.
DR   PRIDE; P16589; -.
DR   EvolutionaryTrace; P16589; -.
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   SUPFAM; SSF100895; SSF100895; 1.
DR   PROSITE; PS51465; KAZAL_2; 1.
PE   1: Evidence at protein level;
KW   3D-structure; Direct protein sequencing; Disulfide bond;
KW   Protease inhibitor; Secreted; Serine protease inhibitor.
FT   CHAIN           1..55
FT                   /note="Trypsin inhibitor"
FT                   /id="PRO_0000073202"
FT   DOMAIN          1..55
FT                   /note="Kazal-like"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00798"
FT   SITE            16..17
FT                   /note="Reactive bond"
FT   DISULFID        5..40
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00798,
FT                   ECO:0000269|PubMed:2111316"
FT   DISULFID        12..41
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00798,
FT                   ECO:0000269|PubMed:2111316"
FT   DISULFID        14..37
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00798,
FT                   ECO:0000269|PubMed:2111316"
FT   DISULFID        23..54
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00798,
FT                   ECO:0000269|PubMed:2111316"
FT   STRAND          8..10
FT                   /evidence="ECO:0007829|PDB:1IW4"
FT   STRAND          22..25
FT                   /evidence="ECO:0007829|PDB:1IW4"
FT   STRAND          31..34
FT                   /evidence="ECO:0007829|PDB:1IW4"
FT   HELIX           36..42
FT                   /evidence="ECO:0007829|PDB:1IW4"
SQ   SEQUENCE   55 AA;  6078 MW;  4121548DB33207C2 CRC64;
     AHMDCTEFNP LCRCNKMLGD LICAVIGDAK EEHRNMCALC CEHPGGFEYS NGPCE