ID   SCX3_CENNO              Reviewed;          66 AA.
AC   P80076;
DT   01-MAR-1992, integrated into UniProtKB/Swiss-Prot.
DT   01-MAR-1992, sequence version 1.
DT   03-AUG-2022, entry version 82.
DE   RecName: Full=Toxin Cn3;
DE            Short=Toxin 3;
DE   AltName: Full=Toxin II.9.2.3;
OS   Centruroides noxius (Mexican scorpion).
OC   Eukaryota; Metazoa; Ecdysozoa; Arthropoda; Chelicerata; Arachnida;
OC   Scorpiones; Buthida; Buthoidea; Buthidae; Centruroides.
OX   NCBI_TaxID=6878;
RN   [1]
RP   PROTEIN SEQUENCE.
RC   TISSUE=Venom;
RX   PubMed=1371253; DOI=10.1111/j.1432-1033.1992.tb16635.x;
RA   Zamudio F.Z., Saavedra R., Martin B.M., Gurrola G.B., Herion P.,
RA   Possani L.D.;
RT   "Amino acid sequence and immunological characterization with monoclonal
RT   antibodies of two toxins from the venom of the scorpion Centruroides noxius
RT   Hoffmann.";
RL   Eur. J. Biochem. 204:281-292(1992).
CC   -!- FUNCTION: Beta toxins bind voltage-independently at site-4 of sodium
CC       channels (Nav) and shift the voltage of activation toward more negative
CC       potentials thereby affecting sodium channel activation and promoting
CC       spontaneous and repetitive firing. {ECO:0000250}.
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   -!- SIMILARITY: Belongs to the long (4 C-C) scorpion toxin superfamily.
CC       Sodium channel inhibitor family. Beta subfamily. {ECO:0000305}.
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DR   PIR; S23080; S23080.
DR   AlphaFoldDB; P80076; -.
DR   SMR; P80076; -.
DR   PRIDE; P80076; -.
DR   GO; GO:0005576; C:extracellular region; IEA:UniProtKB-SubCell.
DR   GO; GO:0019871; F:sodium channel inhibitor activity; IEA:InterPro.
DR   GO; GO:0090729; F:toxin activity; IEA:UniProtKB-KW.
DR   GO; GO:0006952; P:defense response; IEA:InterPro.
DR   Gene3D; 3.30.30.10; -; 1.
DR   InterPro; IPR044062; LCN-type_CS_alpha_beta_dom.
DR   InterPro; IPR003614; Scorpion_toxin-like.
DR   InterPro; IPR036574; Scorpion_toxin-like_sf.
DR   InterPro; IPR018218; Scorpion_toxinL.
DR   InterPro; IPR002061; Scorpion_toxinL/defensin.
DR   Pfam; PF00537; Toxin_3; 1.
DR   PRINTS; PR00285; SCORPNTOXIN.
DR   SMART; SM00505; Knot1; 1.
DR   SUPFAM; SSF57095; SSF57095; 1.
DR   PROSITE; PS51863; LCN_CSAB; 1.
PE   1: Evidence at protein level;
KW   Direct protein sequencing; Disulfide bond; Ion channel impairing toxin;
KW   Neurotoxin; Secreted; Toxin; Voltage-gated sodium channel impairing toxin.
FT   CHAIN           1..66
FT                   /note="Toxin Cn3"
FT                   /id="PRO_0000066767"
FT   DOMAIN          1..66
FT                   /note="LCN-type CS-alpha/beta"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU01210"
FT   DISULFID        12..65
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU01210"
FT   DISULFID        16..41
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU01210"
FT   DISULFID        25..46
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU01210"
FT   DISULFID        29..48
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU01210"
SQ   SEQUENCE   66 AA;  7553 MW;  DDE6A4C4F77AEFC9 CRC64;
     KEGYLVELGT GCKYECFKLG DNDYCLRECK ARYGKGAGGY CYAFGCWCTQ LYEQAVVWPL
     KNKTCR