ID   VKTI3_ANTFU             Reviewed;          56 AA.
AC   P0DMJ4;
DT   11-JUN-2014, integrated into UniProtKB/Swiss-Prot.
DT   11-JUN-2014, sequence version 1.
DT   25-MAY-2022, entry version 14.
DE   RecName: Full=PI-actitoxin-Afv2b {ECO:0000303|PubMed:22683676};
DE            Short=PI-AITX-Afv2b {ECO:0000303|PubMed:22683676};
DE   AltName: Full=Kunitz-type protease inhibitor AFAPI-III {ECO:0000303|PubMed:18450492};
OS   Anthopleura fuscoviridis (Sea anemone).
OC   Eukaryota; Metazoa; Cnidaria; Anthozoa; Hexacorallia; Actiniaria;
OC   Actiniidae; Anthopleura.
OX   NCBI_TaxID=6111;
RN   [1]
RP   PROTEIN SEQUENCE, FUNCTION, AND TISSUE SPECIFICITY.
RC   TISSUE=Tentacle;
RX   PubMed=18450492; DOI=10.1016/j.cbpb.2008.03.010;
RA   Minagawa S., Sugiyama M., Ishida M., Nagashima Y., Shiomi K.;
RT   "Kunitz-type protease inhibitors from acrorhagi of three species of sea
RT   anemones.";
RL   Comp. Biochem. Physiol. 150B:240-245(2008).
RN   [2]
RP   NOMENCLATURE.
RX   PubMed=22683676; DOI=10.1016/j.toxicon.2012.05.020;
RA   Oliveira J.S., Fuentes-Silva D., King G.F.;
RT   "Development of a rational nomenclature for naming peptide and protein
RT   toxins from sea anemones.";
RL   Toxicon 60:539-550(2012).
CC   -!- FUNCTION: Serine protease inhibitor that is strongly active against
CC       trypsin (900 IU/mg) and moderately active against plasmin.
CC       {ECO:0000269|PubMed:18450492}.
CC   -!- SUBCELLULAR LOCATION: Secreted {ECO:0000305}. Nematocyst {ECO:0000305}.
CC   -!- TISSUE SPECIFICITY: Expressed by acrorhagi.
CC       {ECO:0000269|PubMed:18450492}.
CC   -!- MISCELLANEOUS: Does not inhibit potassium channels (Kv), as well as
CC       metalloproteases, and cysteine proteases (papain and bromelain).
CC       {ECO:0000305|PubMed:18450492}.
CC   -!- SIMILARITY: Belongs to the venom Kunitz-type family. Sea anemone type 2
CC       potassium channel toxin subfamily. {ECO:0000305}.
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DR   AlphaFoldDB; P0DMJ4; -.
DR   SMR; P0DMJ4; -.
DR   GO; GO:0005576; C:extracellular region; IEA:UniProtKB-SubCell.
DR   GO; GO:0042151; C:nematocyst; IEA:UniProtKB-SubCell.
DR   GO; GO:0004867; F:serine-type endopeptidase inhibitor activity; IEA:UniProtKB-KW.
DR   CDD; cd00109; KU; 1.
DR   Gene3D; 4.10.410.10; -; 1.
DR   InterPro; IPR002223; Kunitz_BPTI.
DR   InterPro; IPR036880; Kunitz_BPTI_sf.
DR   InterPro; IPR020901; Prtase_inh_Kunz-CS.
DR   Pfam; PF00014; Kunitz_BPTI; 1.
DR   PRINTS; PR00759; BASICPTASE.
DR   SMART; SM00131; KU; 1.
DR   SUPFAM; SSF57362; SSF57362; 1.
DR   PROSITE; PS00280; BPTI_KUNITZ_1; 1.
DR   PROSITE; PS50279; BPTI_KUNITZ_2; 1.
PE   1: Evidence at protein level;
KW   Direct protein sequencing; Disulfide bond; Nematocyst; Protease inhibitor;
KW   Secreted; Serine protease inhibitor.
FT   CHAIN           1..56
FT                   /note="PI-actitoxin-Afv2b"
FT                   /evidence="ECO:0000269|PubMed:18450492"
FT                   /id="PRO_0000429351"
FT   DOMAIN          5..55
FT                   /note="BPTI/Kunitz inhibitor"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00031"
FT   SITE            15..16
FT                   /note="Reactive bond for trypsin"
FT                   /evidence="ECO:0000250"
FT   DISULFID        5..55
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00031"
FT   DISULFID        14..38
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00031"
FT   DISULFID        30..51
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00031"
SQ   SEQUENCE   56 AA;  5995 MW;  2642BF3F33D2CC7E CRC64;
     VPANCLLPMK VGPCRARVPR FYYNSSSGKC EGFTYGGCGA NANKFQTKAQ CEKACA