ID   KAX36_MESMA             Reviewed;          60 AA.
AC   Q9NII7; Q9UAC7;
DT   19-DEC-2001, integrated into UniProtKB/Swiss-Prot.
DT   01-OCT-2000, sequence version 1.
DT   03-AUG-2022, entry version 98.
DE   RecName: Full=Potassium channel toxin alpha-KTx 3.6;
DE   AltName: Full=BmKTX {ECO:0000303|PubMed:9354615};
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].
RX   PubMed=10698710; DOI=10.1042/bj3460805;
RA   Dai L., Wu J.-J., Gu Y.-H., Lan Z.-D., Ling M.-H., Chi C.-W.;
RT   "Genomic organization of three novel toxins from the scorpion Buthus
RT   martensi Karsch that are active on potassium channels.";
RL   Biochem. J. 346:805-809(2000).
RN   [2]
RP   NUCLEOTIDE SEQUENCE [MRNA].
RA   Wu J.-J., Dai L., Chi C.-W.;
RL   Submitted (JUL-1998) to the EMBL/GenBank/DDBJ databases.
RN   [3]
RP   PROTEIN SEQUENCE OF 23-59, TOXIC DOSE, AMIDATION AT LYS-59, SYNTHESIS OF
RP   23-59, FUNCTION, AND ACTIVITY PROFILE.
RX   PubMed=9354615; DOI=10.1021/bi971044w;
RA   Romi-Lebrun R., Lebrun B., Martin-Eauclaire M.-F., Ishiguro M.,
RA   Escoubas P., Wu F.Q., Hisada M., Pongs O., Nakajima T.;
RT   "Purification, characterization, and synthesis of three novel toxins from
RT   the Chinese scorpion Buthus martensi, which act on K+ channels.";
RL   Biochemistry 36:13473-13482(1997).
RN   [4]
RP   FUNCTION, SUBCELLULAR LOCATION, AND MASS SPECTROMETRY.
RC   TISSUE=Venom;
RX   PubMed=20713119; DOI=10.1016/j.biochi.2010.08.003;
RA   Gao B., Peigneur S., Tytgat J., Zhu S.;
RT   "A potent potassium channel blocker from Mesobuthus eupeus scorpion
RT   venom.";
RL   Biochimie 92:1847-1853(2010).
RN   [5]
RP   FUNCTION.
RX   PubMed=26817841; DOI=10.1074/jbc.m115.680611;
RA   Meng L., Xie Z., Zhang Q., Li Y., Yang F., Chen Z., Li W., Cao Z., Wu Y.;
RT   "Scorpion potassium channel-blocking defensin highlights a functional link
RT   with neurotoxin.";
RL   J. Biol. Chem. 291:7097-7106(2016).
RN   [6]
RP   STRUCTURE BY NMR OF 23-59, AND DISULFIDE BONDS.
RX   PubMed=10651040;
RX   DOI=10.1002/(sici)1097-0134(20000101)38:1<70::aid-prot8>3.0.co;2-5;
RA   Renisio J.G., Romi-Lebrun R., Blanc E., Bornet O., Nakajima T., Darbon H.;
RT   "Solution structure of BmKTX, a K+ blocker toxin from the Chinese scorpion
RT   Buthus Martensi.";
RL   Proteins 38:70-78(2000).
CC   -!- FUNCTION: Blocks voltage-gated potassium channels. At 2 uM, blocks rat
CC       Kv1.1/KCNA1 and Kv1.3/KCNA3, has a strong effect on rat Kv1.2/KCNA2 and
CC       Kv1.6/KCNA6 as well as a moderate effect on Shaker IR.
CC       {ECO:0000269|PubMed:20713119, ECO:0000269|PubMed:9354615}.
CC   -!- SUBCELLULAR LOCATION: Secreted {ECO:0000269|PubMed:20713119}.
CC   -!- TISSUE SPECIFICITY: Expressed by the venom gland.
CC       {ECO:0000305|PubMed:20713119}.
CC   -!- DOMAIN: Has the structural arrangement of an alpha-helix connected to a
CC       beta-sheet by disulfide bonds (CSalpha/beta).
CC   -!- MASS SPECTROMETRY: Mass=3960.88; Method=MALDI;
CC       Evidence={ECO:0000269|PubMed:20713119};
CC   -!- TOXIC DOSE: LD(50) is 2.0 ug/kg by intracerebroventricular injection
CC       into mice. {ECO:0000269|PubMed:9354615}.
CC   -!- MISCELLANEOUS: Has no effect on rat Kv1.4/KCNA4, Kv1.5/KCNA5,
CC       Kv4.1/KCND1 or human Kv11.1/KCNH2 and Kv3.1/KCNC1 (PubMed:20713119).
CC       Has no effect on bovine KCa1.1 (PubMed:9354615, PubMed:20713119). Does
CC       not inhibit the growth of Gram-positive and Gram-negative bacteria
CC       (PubMed:26817841). {ECO:0000269|PubMed:20713119,
CC       ECO:0000269|PubMed:26817841, ECO:0000269|PubMed:9354615}.
CC   -!- MISCELLANEOUS: The primary structure of this mature peptide is
CC       identical to that of toxin alpha-KTx 3.19 from Mesobuthus eupeus (AC
CC       C0HJQ6). {ECO:0000305}.
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   EMBL; AF208298; AAF63970.1; -; Genomic_DNA.
DR   EMBL; AF079062; AAD47376.1; -; mRNA.
DR   PDB; 1BKT; NMR; -; A=23-59.
DR   PDB; 2K4U; NMR; -; A=23-59.
DR   PDB; 2MLA; NMR; -; A=23-59.
DR   PDB; 2MLD; NMR; -; A=23-59.
DR   PDBsum; 1BKT; -.
DR   PDBsum; 2K4U; -.
DR   PDBsum; 2MLA; -.
DR   PDBsum; 2MLD; -.
DR   AlphaFoldDB; Q9NII7; -.
DR   BMRB; Q9NII7; -.
DR   SMR; Q9NII7; -.
DR   EvolutionaryTrace; Q9NII7; -.
DR   GO; GO:0005576; C:extracellular region; IDA:UniProtKB.
DR   GO; GO:0019870; F:potassium channel inhibitor activity; IDA:UniProtKB.
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   3D-structure; Amidation; Direct protein sequencing; Disulfide bond;
KW   Ion channel impairing toxin; Neurotoxin; Potassium channel impairing toxin;
KW   Secreted; Signal; Toxin; Voltage-gated potassium channel impairing toxin.
FT   SIGNAL          1..22
FT                   /evidence="ECO:0000269|PubMed:9354615"
FT   CHAIN           23..59
FT                   /note="Potassium channel toxin alpha-KTx 3.6"
FT                   /evidence="ECO:0000269|PubMed:9354615"
FT                   /id="PRO_0000035314"
FT   MOD_RES         59
FT                   /note="Lysine amide"
FT                   /evidence="ECO:0000269|PubMed:9354615"
FT   DISULFID        29..49
FT                   /evidence="ECO:0000269|PubMed:10651040"
FT   DISULFID        35..54
FT                   /evidence="ECO:0000269|PubMed:10651040"
FT   DISULFID        39..56
FT                   /evidence="ECO:0000269|PubMed:10651040"
FT   CONFLICT        14
FT                   /note="C -> S (in Ref. 2; AAD47376)"
FT                   /evidence="ECO:0000305"
FT   STRAND          25..28
FT                   /evidence="ECO:0007829|PDB:2MLA"
FT   TURN            32..35
FT                   /evidence="ECO:0007829|PDB:1BKT"
FT   HELIX           36..41
FT                   /evidence="ECO:0007829|PDB:1BKT"
FT   STRAND          47..49
FT                   /evidence="ECO:0007829|PDB:1BKT"
FT   STRAND          51..56
FT                   /evidence="ECO:0007829|PDB:1BKT"
SQ   SEQUENCE   60 AA;  6462 MW;  6B0985E1223D9E67 CRC64;
     MKVFFAVLIT LFICSMIIGI HGVGINVKCK HSGQCLKPCK DAGMRFGKCI NGKCDCTPKG