ID   VKT3_PALCA              Reviewed;          51 AA.
AC   P0DQR1;
DT   29-SEP-2021, integrated into UniProtKB/Swiss-Prot.
DT   29-SEP-2021, sequence version 1.
DT   03-AUG-2022, entry version 3.
DE   RecName: Full=Kunitz-like toxin PcKuz3 {ECO:0000303|PubMed:29285938};
DE   AltName: Full=Kunitz-type serine protease inhibitor PcKuz3 {ECO:0000305|PubMed:29285938};
DE   AltName: Full=PI-sphenopitoxin-Pc1c {ECO:0000305};
DE            Short=PI-SPTX-Pc1c {ECO:0000305};
OS   Palythoa caribaeorum (White encrusting zoanthid coral).
OC   Eukaryota; Metazoa; Cnidaria; Anthozoa; Hexacorallia; Zoantharia;
OC   Sphenopidae; Palythoa.
OX   NCBI_TaxID=134933;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [MRNA], FUNCTION, SYNTHESIS, TOXIC DOSE, AND
RP   3D-STRUCTURE MODELING.
RX   PubMed=29285938; DOI=10.1021/acs.jproteome.7b00686;
RA   Liao Q., Li S., Siu S.W.I., Yang B., Huang C., Chan J.Y., Morlighem J.R.L.,
RA   Wong C.T.T., Radis-Baptista G., Lee S.M.;
RT   "Novel kunitz-like peptides discovered in the zoanthid Palythoa caribaeorum
RT   through transcriptome sequencing.";
RL   J. Proteome Res. 17:891-902(2018).
CC   -!- FUNCTION: Potent toxin and weak serine protease inhibitor that displays
CC       activity on both trypsin and elastase (PubMed:29285938). May act as a
CC       neurotoxin by blocking voltage-gated potassium channels (Kv1.1/KCNA1
CC       and Kv1.2/KCNA2) (Probable). Has a neuroprotective effect, since it
CC       suppress, at low concentration, the 6-hydroxydopamine-induced
CC       neurotoxicity on the locomotive behavior of zebrafish
CC       (PubMed:29285938). In vivo, has strong reversible antilocomotor
CC       activity (PubMed:29285938). In addition, it is lethal to zebrafish
CC       larvae at high doses (PubMed:29285938). {ECO:0000269|PubMed:29285938,
CC       ECO:0000305|PubMed:29285938}.
CC   -!- SUBCELLULAR LOCATION: Secreted {ECO:0000305}. Nematocyst {ECO:0000305}.
CC   -!- TOXIC DOSE: LD(50) is 10-20 uM against zebrafish larvae.
CC       {ECO:0000269|PubMed:29285938}.
CC   -!- SIMILARITY: Belongs to the venom Kunitz-type family. Sea anemone type 2
CC       potassium channel toxin subfamily. {ECO:0000305}.
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   SMR; P0DQR1; -.
DR   GO; GO:0005576; C:extracellular region; IEA:UniProtKB-SubCell.
DR   GO; GO:0042151; C:nematocyst; IEA:UniProtKB-SubCell.
DR   GO; GO:0015459; F:potassium channel regulator activity; IEA:UniProtKB-KW.
DR   GO; GO:0004867; F:serine-type endopeptidase inhibitor activity; IEA:UniProtKB-KW.
DR   GO; GO:0090729; F:toxin 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   3: Inferred from homology;
KW   Disulfide bond; Ion channel impairing toxin; Nematocyst; Neurotoxin;
KW   Potassium channel impairing toxin; Protease inhibitor; Secreted;
KW   Serine protease inhibitor; Toxin;
KW   Voltage-gated potassium channel impairing toxin.
FT   CHAIN           1..51
FT                   /note="Kunitz-like toxin PcKuz3"
FT                   /evidence="ECO:0000305|PubMed:29285938"
FT                   /id="PRO_0000453751"
FT   DISULFID        1..51
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00031"
FT   DISULFID        10..34
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00031"
FT   DISULFID        26..47
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00031"
SQ   SEQUENCE   51 AA;  5762 MW;  20F5D70E80B6E6AB CRC64;
     CQQPVKPGLC EAYIPRFFYN TSSKQCEKFI YGGCGGNSNR FLTMKACQDK C