ID   VKT31_MESMA             Reviewed;          81 AA.
AC   P0DJ50;
DT   11-JUL-2012, integrated into UniProtKB/Swiss-Prot.
DT   11-JUN-2014, sequence version 2.
DT   25-MAY-2022, entry version 25.
DE   RecName: Full=Kunitz-type serine protease inhibitor BmKTT-2;
DE   AltName: Full=Delta-KTx 3.1;
DE   Flags: Precursor;
OS   Mesobuthus martensii (Manchurian scorpion) (Buthus martensii).
OC   Eukaryota; Metazoa; Ecdysozoa; Arthropoda; Chelicerata; Arachnida;
OC   Scorpiones; Buthida; Buthoidea; Buthidae; Mesobuthus.
OX   NCBI_TaxID=34649;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA], AND NOMENCLATURE.
RX   PubMed=23573241; DOI=10.1371/journal.pone.0060201;
RA   Chen Z., Luo F., Feng J., Yang W., Zeng D., Zhao R., Cao Z., Liu M., Li W.,
RA   Jiang L., Wu Y.;
RT   "Genomic and structural characterization of Kunitz-type peptide LmKTT-1a
RT   highlights diversity and evolution of scorpion potassium channel toxins.";
RL   PLoS ONE 8:E60201-E60201(2013).
RN   [2]
RP   NUCLEOTIDE SEQUENCE [MRNA] OF 24-81, AND FUNCTION.
RC   TISSUE=Venom gland;
RX   PubMed=22354971; DOI=10.1074/jbc.m112.343996;
RA   Chen Z.-Y., Hu Y.T., Yang W.S., He Y.W., Feng J., Wang B., Zhao R.M.,
RA   Ding J.P., Cao Z.-J., Li W.-X., Wu Y.-L.;
RT   "Hg1, novel peptide inhibitor specific for Kv1.3 channels from first
RT   scorpion Kunitz-type potassium channel toxin family.";
RL   J. Biol. Chem. 287:13813-13821(2012).
CC   -!- FUNCTION: Dual-function toxin that completely inhibits trypsin activity
CC       at a molar ratio of 1:1 (dissociation constant of 420 nM) and that
CC       inhibits mKv1.3/KCNA3 potassium channel currents with an IC(50) of
CC       371.3 nM. {ECO:0000269|PubMed:22354971}.
CC   -!- SUBCELLULAR LOCATION: Secreted {ECO:0000250}.
CC   -!- TISSUE SPECIFICITY: Expressed by the venom gland.
CC   -!- MISCELLANEOUS: Has no effect on chymotrypsin and elastase.
CC       {ECO:0000305|PubMed:22354971}.
CC   -!- SIMILARITY: Belongs to the venom Kunitz-type family. Scorpion delta-Ktx
CC       subfamily. Delta-Ktx 3 sub-subfamily. {ECO:0000305}.
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DR   AlphaFoldDB; P0DJ50; -.
DR   SMR; P0DJ50; -.
DR   GO; GO:0005576; C:extracellular region; NAS:UniProtKB.
DR   GO; GO:0033644; C:host cell membrane; NAS:UniProtKB.
DR   GO; GO:0015459; F:potassium channel regulator activity; IEA:UniProtKB-KW.
DR   GO; GO:0004867; F:serine-type endopeptidase inhibitor activity; IDA:UniProtKB.
DR   GO; GO:0090729; F:toxin activity; IEA:UniProtKB-KW.
DR   GO; GO:0044562; P:envenomation resulting in negative regulation of voltage-gated potassium channel activity in another organism; IDA:UniProtKB.
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   2: Evidence at transcript level;
KW   Disulfide bond; Ion channel impairing toxin;
KW   Potassium channel impairing toxin; Protease inhibitor; Secreted;
KW   Serine protease inhibitor; Signal; Toxin;
KW   Voltage-gated potassium channel impairing toxin.
FT   SIGNAL          1..21
FT                   /evidence="ECO:0000255"
FT   CHAIN           22..81
FT                   /note="Kunitz-type serine protease inhibitor BmKTT-2"
FT                   /id="PRO_0000418105"
FT   DOMAIN          26..76
FT                   /note="BPTI/Kunitz inhibitor"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00031"
FT   SITE            36..37
FT                   /note="Reactive bond for trypsin"
FT                   /evidence="ECO:0000250"
FT   DISULFID        26..76
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00031"
FT   DISULFID        35..59
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00031"
FT   DISULFID        51..72
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00031"
FT   DISULFID        73..81
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00031"
SQ   SEQUENCE   81 AA;  8825 MW;  F43EC67637FDFA16 CRC64;
     MMNVITVVGI ILSVVCTISD AEGVDCTLPS DTGRCKAYFI RYFYNQKAGE CQKFVYGGCE
     GNSNNFLTKS DCCKQCSPGK C