ID   KAX43_TITDI             Reviewed;          37 AA.
AC   P59925;
DT   24-OCT-2003, integrated into UniProtKB/Swiss-Prot.
DT   24-OCT-2003, sequence version 1.
DT   25-MAY-2022, entry version 64.
DE   RecName: Full=Potassium channel toxin alpha-KTx 4.3;
DE   AltName: Full=Toxin TdK1;
OS   Tityus discrepans (Venezuelan scorpion).
OC   Eukaryota; Metazoa; Ecdysozoa; Arthropoda; Chelicerata; Arachnida;
OC   Scorpiones; Buthida; Buthoidea; Buthidae; Tityus.
OX   NCBI_TaxID=57059;
RN   [1]
RP   PROTEIN SEQUENCE, AND MASS SPECTROMETRY.
RC   TISSUE=Venom;
RX   PubMed=10452547; DOI=10.1016/s0014-5793(99)00947-3;
RA   D'Suze G., Zamudio F., Gomez-Lagunas F., Possani L.D.;
RT   "A novel K+ channel blocking toxin from Tityus discrepans scorpion venom.";
RL   FEBS Lett. 456:146-148(1999).
RN   [2]
RP   PROTEIN SEQUENCE OF 1-10, AND MASS SPECTROMETRY.
RX   PubMed=16705749; DOI=10.1002/pmic.200500525;
RA   Batista C.V.F., D'Suze G., Gomez-Lagunas F., Zamudio F.Z., Encarnacion S.,
RA   Sevcik C., Possani L.D.;
RT   "Proteomic analysis of Tityus discrepans scorpion venom and amino acid
RT   sequence of novel toxins.";
RL   Proteomics 6:3718-3727(2006).
CC   -!- FUNCTION: Blocks reversibly Shaker B potassium-channels.
CC   -!- SUBCELLULAR LOCATION: Secreted.
CC   -!- TISSUE SPECIFICITY: Expressed by the venom gland.
CC   -!- DOMAIN: Has the structural arrangement of an alpha-helix connected to
CC       antiparallel beta-sheets by disulfide bonds (CS-alpha/beta).
CC       {ECO:0000305}.
CC   -!- MASS SPECTROMETRY: Mass=3816.8; Method=MALDI;
CC       Evidence={ECO:0000269|PubMed:10452547};
CC   -!- MASS SPECTROMETRY: Mass=3816; Method=Electrospray;
CC       Evidence={ECO:0000269|PubMed:16705749};
CC   -!- SIMILARITY: Belongs to the short scorpion toxin superfamily. Potassium
CC       channel inhibitor family. Alpha-KTx 04 subfamily. {ECO:0000305}.
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DR   AlphaFoldDB; P59925; -.
DR   SMR; P59925; -.
DR   GO; GO:0005576; C:extracellular region; IEA:UniProtKB-SubCell.
DR   GO; GO:0008200; F:ion channel inhibitor activity; IEA:InterPro.
DR   GO; GO:0015459; F:potassium channel regulator activity; IEA:UniProtKB-KW.
DR   GO; GO:0090729; F:toxin activity; IEA:UniProtKB-KW.
DR   Gene3D; 3.30.30.10; -; 1.
DR   InterPro; IPR036574; Scorpion_toxin-like_sf.
DR   InterPro; IPR001947; Scorpion_toxinS_K_inh.
DR   Pfam; PF00451; Toxin_2; 1.
DR   PRINTS; PR00286; CHARYBDTOXIN.
DR   SUPFAM; SSF57095; SSF57095; 1.
DR   PROSITE; PS01138; SCORP_SHORT_TOXIN; 1.
PE   1: Evidence at protein level;
KW   Direct protein sequencing; Disulfide bond; Ion channel impairing toxin;
KW   Neurotoxin; Potassium channel impairing toxin; Secreted; Toxin.
FT   PEPTIDE         1..37
FT                   /note="Potassium channel toxin alpha-KTx 4.3"
FT                   /id="PRO_0000044922"
FT   REGION          26..33
FT                   /note="Interaction with Ca(2+)-activated K(+) channels"
FT                   /evidence="ECO:0000255"
FT   SITE            27
FT                   /note="Basic residue of the functional dyad"
FT                   /evidence="ECO:0000250"
FT   SITE            36
FT                   /note="Aromatic residue of the functional dyad"
FT                   /evidence="ECO:0000250"
FT   DISULFID        7..28
FT                   /evidence="ECO:0000250"
FT   DISULFID        13..33
FT                   /evidence="ECO:0000250"
FT   DISULFID        17..35
FT                   /evidence="ECO:0000250"
SQ   SEQUENCE   37 AA;  3826 MW;  6DC2FA311C38542F CRC64;
     VFINVKCTGS KQCLPACKAA VGKAAGKCMN GKCKCYT