ID   KAX39_BUTOC             Reviewed;          37 AA.
AC   P59290;
DT   12-FEB-2003, integrated into UniProtKB/Swiss-Prot.
DT   12-FEB-2003, sequence version 1.
DT   25-MAY-2022, entry version 71.
DE   RecName: Full=Potassium channel toxin alpha-KTx 3.9;
DE   AltName: Full=Kaliotoxin-3;
DE            Short=KTX-3;
GN   Name=KTX3;
OS   Buthus occitanus tunetanus (Common European scorpion) (Buthus tunetanus).
OC   Eukaryota; Metazoa; Ecdysozoa; Arthropoda; Chelicerata; Arachnida;
OC   Scorpiones; Buthida; Buthoidea; Buthidae; Buthus.
OX   NCBI_TaxID=6871;
RN   [1]
RP   PROTEIN SEQUENCE, TOXIC DOSE, AND MASS SPECTROMETRY.
RC   TISSUE=Venom;
RX   PubMed=10669015; DOI=10.1016/s0041-0101(99)00137-3;
RA   Meki A., Mansuelle P., Laraba-Djebari F., Oughideni R., Rochat H.,
RA   Martin-Eauclaire M.-F.;
RT   "KTX3, the kaliotoxin from Buthus occitanus tunetanus scorpion venom: one
RT   of an extensive family of peptidyl ligands of potassium channels.";
RL   Toxicon 38:105-111(2000).
CC   -!- FUNCTION: Binds and inhibits potassium channels.
CC       Intracerebroventricular injection into mice induces paralyzing symptoms
CC       followed by death. Its binding affinity to rat brain synaptosomes is 5-
CC       fold lower than this of KTX 1.
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=4376.27; Method=Electrospray;
CC       Evidence={ECO:0000269|PubMed:10669015};
CC   -!- TOXIC DOSE: LD(50) is 5.5 ug/kg by intracerebroventricular injection.
CC       {ECO:0000269|PubMed:10669015}.
CC   -!- SIMILARITY: Belongs to the short scorpion toxin superfamily. Potassium
CC       channel inhibitor family. Alpha-KTx 03 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   AlphaFoldDB; P59290; -.
DR   SMR; P59290; -.
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 3.9"
FT                   /id="PRO_0000044897"
FT   REGION          25..32
FT                   /note="Interaction with Ca(2+)-activated K(+) channels"
FT                   /evidence="ECO:0000255"
FT   DISULFID        7..27
FT                   /evidence="ECO:0000250"
FT   DISULFID        13..32
FT                   /evidence="ECO:0000250"
FT   DISULFID        17..34
FT                   /evidence="ECO:0000250"
SQ   SEQUENCE   37 AA;  4028 MW;  D3A9805D5B55D8CB CRC64;
     VGIPVSCKHS GQCIKPCKDA GMRFGKCMNR KCDCTPK