ID   SCXM_CENSC              Reviewed;          65 AA.
AC   P56646;
DT   15-JUL-1999, integrated into UniProtKB/Swiss-Prot.
DT   15-JUL-1999, sequence version 1.
DT   03-AUG-2022, entry version 80.
DE   RecName: Full=Toxin CsEM1;
DE            Short=CsE M1;
DE   AltName: Full=CsEIII;
OS   Centruroides sculpturatus (Arizona bark scorpion).
OC   Eukaryota; Metazoa; Ecdysozoa; Arthropoda; Chelicerata; Arachnida;
OC   Scorpiones; Buthida; Buthoidea; Buthidae; Centruroides.
OX   NCBI_TaxID=218467;
RN   [1]
RP   PROTEIN SEQUENCE, AND TOXIC DOSE.
RC   TISSUE=Venom;
RX   PubMed=1286943; DOI=10.1111/j.1399-3011.1992.tb00444.x;
RA   Pete M.J., Conlon J.M., Murphy R.F.;
RT   "Isolation and primary structure of a potent toxin from the venom of the
RT   scorpion Centruroides sculpturatus Ewing.";
RL   Int. J. Pept. Protein Res. 40:582-586(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 (By similarity). Highly potent.
CC       {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   -!- TOXIC DOSE: LD(50) is 87 mg/kg by subcutaneous injection in mouse.
CC       {ECO:0000269|PubMed:1286943}.
CC   -!- SIMILARITY: Belongs to the long (4 C-C) scorpion toxin superfamily.
CC       Sodium channel inhibitor family. Beta 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; P56646; -.
DR   SMR; P56646; -.
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..65
FT                   /note="Toxin CsEM1"
FT                   /id="PRO_0000066776"
FT   DOMAIN          1..65
FT                   /note="LCN-type CS-alpha/beta"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU01210"
FT   DISULFID        12..64
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU01210"
FT   DISULFID        16..40
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU01210"
FT   DISULFID        25..45
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU01210"
FT   DISULFID        29..47
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU01210"
SQ   SEQUENCE   65 AA;  7550 MW;  56BDA312F17D3C9C CRC64;
     KEGYLVNSYT GCKYECLKLG DNDYCLRECR QQYGKSGGYC YAFACWCTHL YEQAVVWPLP
     NKTCN