ID   SCXI_CENSC              Reviewed;          86 AA.
AC   P01491; Q95WC1;
DT   21-JUL-1986, integrated into UniProtKB/Swiss-Prot.
DT   16-APR-2002, sequence version 3.
DT   03-AUG-2022, entry version 108.
DE   RecName: Full=Beta-toxin CsEI;
DE            Short=CsE-I;
DE   AltName: Full=Neurotoxin I;
DE   Flags: Precursor;
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   NUCLEOTIDE SEQUENCE [MRNA].
RC   TISSUE=Venom gland;
RX   PubMed=11600153; DOI=10.1016/s0041-0101(01)00174-x;
RA   Corona M., Valdez-Cruz N.A., Merino E., Zurita M., Possani L.D.;
RT   "Genes and peptides from the scorpion Centruroides sculpturatus Ewing, that
RT   recognize Na(+)-channels.";
RL   Toxicon 39:1893-1898(2001).
RN   [2]
RP   PROTEIN SEQUENCE OF 20-83.
RX   PubMed=1122130; DOI=10.1016/0003-9861(75)90371-9;
RA   Babin D.R., Watt D.D., Goos S.M., Mlejnek R.V.;
RT   "Amino acid sequence of neurotoxin I from Centruroides sculpturatus
RT   Ewing.";
RL   Arch. Biochem. Biophys. 166:125-134(1975).
RN   [3]
RP   STRUCTURE BY NMR, AND DISULFIDE BONDS.
RX   PubMed=9918851; DOI=10.1006/bbrc.1998.9904;
RA   Jablonsky M.J., Jackson P.L., Trent J.O., Watt D.D., Krishna N.R.;
RT   "Solution structure of a beta-neurotoxin from the New World scorpion
RT   Centruroides sculpturatus Ewing.";
RL   Biochem. Biophys. Res. Commun. 254:406-412(1999).
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. Affects channels from chicken and
CC       frog.
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   EMBL; AF338460; AAL23428.1; -; mRNA.
DR   PIR; A01751; NTSRIC.
DR   PDB; 1B3C; NMR; -; A=20-83.
DR   PDB; 2B3C; NMR; -; A=20-83.
DR   PDBsum; 1B3C; -.
DR   PDBsum; 2B3C; -.
DR   AlphaFoldDB; P01491; -.
DR   BMRB; P01491; -.
DR   SMR; P01491; -.
DR   EvolutionaryTrace; P01491; -.
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   3D-structure; Amidation; Direct protein sequencing; Disulfide bond;
KW   Ion channel impairing toxin; Neurotoxin; Secreted; Signal; Toxin;
KW   Voltage-gated sodium channel impairing toxin.
FT   SIGNAL          1..19
FT                   /evidence="ECO:0000269|PubMed:1122130"
FT   PEPTIDE         20..83
FT                   /note="Beta-toxin CsEI"
FT                   /id="PRO_0000035294"
FT   DOMAIN          20..84
FT                   /note="LCN-type CS-alpha/beta"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU01210"
FT   MOD_RES         83
FT                   /note="Cysteine amide"
FT                   /evidence="ECO:0000255"
FT   DISULFID        30..83
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU01210,
FT                   ECO:0000269|PubMed:9918851"
FT   DISULFID        34..59
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU01210,
FT                   ECO:0000269|PubMed:9918851"
FT   DISULFID        43..64
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU01210,
FT                   ECO:0000269|PubMed:9918851"
FT   DISULFID        47..66
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU01210,
FT                   ECO:0000269|PubMed:9918851"
FT   CONFLICT        59
FT                   /note="C -> F (in Ref. 1; AAL23428)"
FT                   /evidence="ECO:0000305"
FT   CONFLICT        82..83
FT                   /note="TC -> CT (in Ref. 2; AA sequence)"
FT                   /evidence="ECO:0000305"
FT   STRAND          21..23
FT                   /evidence="ECO:0007829|PDB:1B3C"
FT   HELIX           41..47
FT                   /evidence="ECO:0007829|PDB:1B3C"
FT   STRAND          48..50
FT                   /evidence="ECO:0007829|PDB:1B3C"
FT   STRAND          56..68
FT                   /evidence="ECO:0007829|PDB:1B3C"
FT   STRAND          79..81
FT                   /evidence="ECO:0007829|PDB:1B3C"
SQ   SEQUENCE   86 AA;  9634 MW;  81CDD3CEAA75B2CF CRC64;
     MNSLLMITAC LVLIGTVWAK DGYLVEKTGC KKTCYKLGEN DFCNRECKWK HIGGSYGYCY
     GFGCYCEGLP DSTQTWPLPN KTCGKK