VKT22_LYCMC
ID VKT22_LYCMC Reviewed; 80 AA.
AC P0DJ45; P0CJ20;
DT 11-JUL-2012, integrated into UniProtKB/Swiss-Prot.
DT 11-JUL-2012, sequence version 1.
DT 25-MAY-2022, entry version 24.
DE RecName: Full=Kunitz-type serine protease inhibitor LmKTT-1b;
DE AltName: Full=Delta-KTx 2.2;
DE AltName: Full=SdPI;
DE Flags: Precursor;
OS Lychas mucronatus (Chinese swimming scorpion).
OC Eukaryota; Metazoa; Ecdysozoa; Arthropoda; Chelicerata; Arachnida;
OC Scorpiones; Buthida; Buthoidea; Buthidae; Lychas.
OX NCBI_TaxID=172552;
RN [1]
RP NUCLEOTIDE SEQUENCE [MRNA].
RC STRAIN=Yunnan; TISSUE=Venom gland;
RX PubMed=20663230; DOI=10.1186/1471-2164-11-452;
RA Zhao R., Ma Y., He Y., Di Z., Wu Y.-L., Cao Z.-J., Li W.-X.;
RT "Comparative venom gland transcriptome analysis of the scorpion Lychas
RT mucronatus reveals intraspecific toxic gene diversity and new venomous
RT components.";
RL BMC Genomics 11:452-452(2010).
RN [2]
RP FUNCTION, MUTAGENESIS OF LYS-33; GLY-34; LYS-35 AND ALA-36, AND
RP 3D-STRUCTURE MODELING.
RX PubMed=22087336; DOI=10.1371/journal.pone.0027548;
RA Zhao R.M., Dai H., Qiu S., Li T., He Y., Ma Y., Chen Z.-Y., Wu Y.-L.,
RA Li W.-X., Cao Z.-J.;
RT "SdPI, the first functionally characterized Kunitz-type trypsin inhibitor
RT from scorpion venom.";
RL PLoS ONE 6:E27548-E27548(2011).
RN [3]
RP FUNCTION.
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 160 nM) and that
CC inhibits mKv1.3/KCNA3 potassium channel currents (1 uM inhibits 50% of
CC currents). It is thermostable. {ECO:0000269|PubMed:22087336,
CC 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 (PubMed:22087336 and PubMed:22354971).
CC -!- SIMILARITY: Belongs to the venom Kunitz-type family. Scorpion delta-Ktx
CC subfamily. Delta-Ktx 2 sub-subfamily. {ECO:0000305}.
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DR EMBL; GT028613; -; NOT_ANNOTATED_CDS; mRNA.
DR AlphaFoldDB; P0DJ45; -.
DR SMR; P0DJ45; -.
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 Pfam; PF00014; Kunitz_BPTI; 1.
DR PRINTS; PR00759; BASICPTASE.
DR SMART; SM00131; KU; 1.
DR SUPFAM; SSF57362; SSF57362; 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..80
FT /note="Kunitz-type serine protease inhibitor LmKTT-1b"
FT /id="PRO_0000403912"
FT DOMAIN 25..75
FT /note="BPTI/Kunitz inhibitor"
FT /evidence="ECO:0000255|PROSITE-ProRule:PRU00031"
FT SITE 35
FT /note="Key residue that directly interacts with the S1
FT pocket of trypsin"
FT DISULFID 25..75
FT /evidence="ECO:0000255|PROSITE-ProRule:PRU00031"
FT DISULFID 50..71
FT /evidence="ECO:0000255|PROSITE-ProRule:PRU00031"
FT DISULFID 72..80
FT /evidence="ECO:0000255|PROSITE-ProRule:PRU00031"
FT MUTAGEN 33
FT /note="K->A: 1.8-fold decrease in trypsin inhibitory
FT activity."
FT /evidence="ECO:0000269|PubMed:22087336"
FT MUTAGEN 34
FT /note="G->F: 1.6-fold decrease in trypsin inhibitory
FT activity."
FT /evidence="ECO:0000269|PubMed:22087336"
FT MUTAGEN 35
FT /note="K->A: Loss of trypsin inhibitory activity."
FT /evidence="ECO:0000269|PubMed:22087336"
FT MUTAGEN 36
FT /note="A->F: 400-fold decrease in trypsin inhibitory
FT activity."
FT /evidence="ECO:0000269|PubMed:22087336"
SQ SEQUENCE 80 AA; 8820 MW; D82F7CC78B8F8CBC CRC64;
MKSFLLIALV LFFLFVSYAS AKNKCQLPSD VGKGKASFTR YYYNEEGGKC ETFIYGGVGG
NSNNFLTKED CCRECAQGSC
