ID   IATR_HORSE              Reviewed;         125 AA.
AC   P04365;
DT   20-MAR-1987, integrated into UniProtKB/Swiss-Prot.
DT   09-NOV-2004, sequence version 2.
DT   25-MAY-2022, entry version 109.
DE   RecName: Full=Inter-alpha-trypsin inhibitor;
DE            Short=ITI;
DE   AltName: Full=EI-14;
DE   AltName: Full=HI-14;
DE   AltName: Full=Inhibitory fragment of ITI;
DE   Flags: Fragment;
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 OF 3-125.
RX   PubMed=2408637; DOI=10.1515/bchm3.1985.366.1.473;
RA   Hochstrasser K., Wachter E., Albrecht G.J., Reisinger P.;
RT   "Kunitz-type proteinase inhibitors derived by limited proteolysis of the
RT   inter-alpha-trypsin inhibitor, X. The amino-acid sequences of the trypsin-
RT   released inhibitors from horse and pig inter-alpha-trypsin inhibitors.";
RL   Biol. Chem. Hoppe-Seyler 366:473-478(1985).
RN   [2]
RP   PROTEIN SEQUENCE OF 1-31.
RC   TISSUE=Urine;
RX   PubMed=1627153;
RA   Veeraragavan K., Singh K., Wachter E., Hochstrasser K.;
RT   "Characterization of a trypsin inhibitor from equine urine.";
RL   Biochem. Int. 26:405-413(1992).
CC   -!- FUNCTION: This inhibitory fragment, released from native ITI after
CC       limited proteolysis with trypsin, contains two homologous domains.
CC       Whereas the second domain is a strong inhibitor of trypsin, the first
CC       domain interacts weakly with PMN-granulocytic elastase and not at all
CC       with pancreatic elastase.
CC   -!- SUBCELLULAR LOCATION: Secreted.
CC   -!- MISCELLANEOUS: The amino acid at position p2' (17) appears to determine
CC       the specificity of the inhibition of domain I. Inhibitors with
CC       methionine in this position interact weakly with chymotrypsin and
CC       elastase; those with leucine interact strongly.
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DR   PIR; A01210; TIHOBI.
DR   AlphaFoldDB; P04365; -.
DR   SMR; P04365; -.
DR   STRING; 9796.ENSECAP00000046787; -.
DR   MEROPS; I02.005; -.
DR   PaxDb; P04365; -.
DR   PeptideAtlas; P04365; -.
DR   Proteomes; UP000002281; Unplaced.
DR   GO; GO:0009986; C:cell surface; IBA:GO_Central.
DR   GO; GO:0005576; C:extracellular region; IEA:UniProtKB-SubCell.
DR   GO; GO:0005886; C:plasma membrane; IBA:GO_Central.
DR   GO; GO:0004867; F:serine-type endopeptidase inhibitor activity; IBA:GO_Central.
DR   CDD; cd00109; KU; 2.
DR   Gene3D; 4.10.410.10; -; 2.
DR   InterPro; IPR029856; AMBP.
DR   InterPro; IPR002223; Kunitz_BPTI.
DR   InterPro; IPR036880; Kunitz_BPTI_sf.
DR   InterPro; IPR020901; Prtase_inh_Kunz-CS.
DR   PANTHER; PTHR46676; PTHR46676; 1.
DR   Pfam; PF00014; Kunitz_BPTI; 2.
DR   PRINTS; PR00759; BASICPTASE.
DR   SMART; SM00131; KU; 2.
DR   SUPFAM; SSF57362; SSF57362; 2.
DR   PROSITE; PS00280; BPTI_KUNITZ_1; 2.
DR   PROSITE; PS50279; BPTI_KUNITZ_2; 2.
PE   1: Evidence at protein level;
KW   Direct protein sequencing; Disulfide bond; Glycoprotein;
KW   Protease inhibitor; Reference proteome; Repeat; Secreted;
KW   Serine protease inhibitor.
FT   CHAIN           <1..>125
FT                   /note="Inter-alpha-trypsin inhibitor"
FT                   /id="PRO_0000155405"
FT   DOMAIN          7..57
FT                   /note="BPTI/Kunitz inhibitor 1"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00031"
FT   DOMAIN          63..113
FT                   /note="BPTI/Kunitz inhibitor 2"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00031"
FT   SITE            17..18
FT                   /note="Reactive bond for chymotrypsin and elastase"
FT   SITE            73..74
FT                   /note="Reactive bond for trypsin"
FT   CARBOHYD        26
FT                   /note="N-linked (GlcNAc...) asparagine"
FT   DISULFID        7..57
FT   DISULFID        16..40
FT   DISULFID        32..53
FT   DISULFID        63..113
FT   DISULFID        72..96
FT   DISULFID        88..109
FT   CONFLICT        13
FT                   /note="Q -> E (in Ref. 2; AA sequence)"
FT                   /evidence="ECO:0000305"
FT   NON_TER         1
FT   NON_TER         125
SQ   SEQUENCE   125 AA;  13726 MW;  CE79B4D801DF42D5 CRC64;
     SKKEDSCQLD HAQGPCLGMI SRYFYNGTSM ACETFQYGGC LGNGNNFASQ KECLQTCRTV
     AACNLPIVQG PCRAFIRLWA FDAAQGKCVL FTYGGCRGNG NKFYSQKECK EYCGIPGDGD
     EELLR