ID   KAX45_TITCO             Reviewed;          59 AA.
AC   Q5G8B6;
DT   04-APR-2006, integrated into UniProtKB/Swiss-Prot.
DT   01-MAR-2005, sequence version 1.
DT   25-MAY-2022, entry version 50.
DE   RecName: Full=Potassium channel toxin alpha-KTx 4.5 {ECO:0000303|PubMed:15683865};
DE   Flags: Precursor;
OS   Tityus costatus (Brazilian scorpion).
OC   Eukaryota; Metazoa; Ecdysozoa; Arthropoda; Chelicerata; Arachnida;
OC   Scorpiones; Buthida; Buthoidea; Buthidae; Tityus.
OX   NCBI_TaxID=309814;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [MRNA], MASS SPECTROMETRY, AND SUBCELLULAR LOCATION.
RC   TISSUE=Venom, and Venom gland;
RX   PubMed=15683865; DOI=10.1016/j.toxicon.2004.10.014;
RA   Diego-Garcia E., Batista C.V.F., Garcia-Gomez B.I., Lucas S., Candido D.M.,
RA   Gomez-Lagunas F., Possani L.D.;
RT   "The Brazilian scorpion Tityus costatus Karsch: genes, peptides and
RT   function.";
RL   Toxicon 45:273-283(2005).
RN   [2]
RP   X-RAY CRYSTALLOGRAPHY (1.76 ANGSTROMS) OF 23-59, SYNTHESIS OF 23-59, AND
RP   DISULFIDE BONDS.
RX   PubMed=29483648; DOI=10.1038/s41594-018-0033-9;
RA   Correnti C.E., Gewe M.M., Mehlin C., Bandaranayake A.D., Johnsen W.A.,
RA   Rupert P.B., Brusniak M.Y., Clarke M., Burke S.E., De Van Der Schueren W.,
RA   Pilat K., Turnbaugh S.M., May D., Watson A., Chan M.K., Bahl C.D.,
RA   Olson J.M., Strong R.K.;
RT   "Screening, large-scale production and structure-based classification of
RT   cystine-dense peptides.";
RL   Nat. Struct. Mol. Biol. 25:270-278(2018).
CC   -!- FUNCTION: Inhibits with low potency Kv1.1/KCNA1, Kv1.2/KCNA2,
CC       Kv1.3/KCNA3 and Kv11.1/KCNH2/ERG1 voltage-gated potassium
CC       channels(PubMed:29483648). {ECO:0000269|PubMed:29483648}.
CC   -!- SUBCELLULAR LOCATION: Secreted {ECO:0000269|PubMed:15683865}.
CC   -!- TISSUE SPECIFICITY: Expressed by the venom gland.
CC       {ECO:0000305|PubMed:15683865}.
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=3986; Method=Electrospray;
CC       Evidence={ECO:0000269|PubMed:15683865};
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   EMBL; AY740685; AAW72455.1; -; mRNA.
DR   PDB; 6ATN; X-ray; 1.76 A; A=23-59.
DR   PDBsum; 6ATN; -.
DR   AlphaFoldDB; Q5G8B6; -.
DR   SMR; Q5G8B6; -.
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   3D-structure; Disulfide bond; Ion channel impairing toxin; Neurotoxin;
KW   Potassium channel impairing toxin; Secreted; Signal; Toxin;
KW   Voltage-gated potassium channel impairing toxin.
FT   SIGNAL          1..22
FT   CHAIN           23..59
FT                   /note="Potassium channel toxin alpha-KTx 4.5"
FT                   /id="PRO_0000231505"
FT   REGION          48..55
FT                   /note="Interaction with Ca(2+)-activated K(+) channels"
FT                   /evidence="ECO:0000255"
FT   SITE            49
FT                   /note="Basic residue of the functional dyad"
FT                   /evidence="ECO:0000250"
FT   SITE            58
FT                   /note="Aromatic residue of the functional dyad"
FT                   /evidence="ECO:0000250"
FT   DISULFID        29..50
FT                   /evidence="ECO:0000269|PubMed:29483648,
FT                   ECO:0000312|PDB:6ATN"
FT   DISULFID        35..55
FT                   /evidence="ECO:0000269|PubMed:29483648,
FT                   ECO:0000312|PDB:6ATN"
FT   DISULFID        39..57
FT                   /evidence="ECO:0000269|PubMed:29483648,
FT                   ECO:0000312|PDB:6ATN"
FT   STRAND          23..28
FT                   /evidence="ECO:0007829|PDB:6ATN"
FT   STRAND          30..32
FT                   /evidence="ECO:0007829|PDB:6ATN"
FT   HELIX           35..43
FT                   /evidence="ECO:0007829|PDB:6ATN"
FT   STRAND          44..46
FT                   /evidence="ECO:0007829|PDB:6ATN"
FT   STRAND          48..51
FT                   /evidence="ECO:0007829|PDB:6ATN"
FT   STRAND          54..57
FT                   /evidence="ECO:0007829|PDB:6ATN"
SQ   SEQUENCE   59 AA;  6518 MW;  6FC51DBA878CCC2B CRC64;
     MKAFYGVLII FILISMLDLS QQVFINVKCR GSPECLPKCK EAIGKSAGKC MNGKCKCYP