ID   SCX4_TITDI              Reviewed;          73 AA.
AC   Q1I174;
DT   17-OCT-2006, integrated into UniProtKB/Swiss-Prot.
DT   13-JUN-2006, sequence version 1.
DT   03-AUG-2022, entry version 41.
DE   RecName: Full=Toxin Td4;
DE   AltName: Full=P*T-beta* NaTx14.3;
DE   Flags: Precursor; Fragment;
OS   Tityus discrepans (Venezuelan scorpion).
OC   Eukaryota; Metazoa; Ecdysozoa; Arthropoda; Chelicerata; Arachnida;
OC   Scorpiones; Buthida; Buthoidea; Buthidae; Tityus.
OX   NCBI_TaxID=57059;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [MRNA], AND MASS SPECTROMETRY.
RC   TISSUE=Venom, and Venom gland;
RX   PubMed=16356783; DOI=10.1016/j.cbpc.2005.10.011;
RA   Borges A., Garcia C.C., Lugo E., Alfonzo M.J., Jowers M.J.,
RA   Op den Camp H.J.M.;
RT   "Diversity of long-chain toxins in Tityus zulianus and Tityus discrepans
RT   venoms (Scorpiones, Buthidae): molecular, immunological, and mass spectral
RT   analyses.";
RL   Comp. Biochem. Physiol. 142C:240-252(2006).
RN   [2]
RP   NOMENCLATURE.
RX   PubMed=22355312; DOI=10.1371/journal.pone.0030478;
RA   Guerrero-Vargas J.A., Mourao C.B., Quintero-Hernandez V., Possani L.D.,
RA   Schwartz E.F.;
RT   "Identification and phylogenetic analysis of Tityus pachyurus and Tityus
RT   obscurus novel putative Na+-channel scorpion toxins.";
RL   PLoS ONE 7:E30478-E30478(2012).
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   -!- MASS SPECTROMETRY: Mass=7367.75; Method=MALDI;
CC       Evidence={ECO:0000269|PubMed:16356783};
CC   -!- MISCELLANEOUS: Does not affect the cardiac Nav1.5/SCN5A, the peripheral
CC       nerve channel Nav1.7/SCN9A, and the voltage-dependent potassium channel
CC       Kv1.5/KCNA5. {ECO:0000250}.
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; DQ075232; AAZ29711.1; -; mRNA.
DR   EMBL; DQ075231; AAZ29710.1; -; mRNA.
DR   AlphaFoldDB; Q1I174; -.
DR   SMR; Q1I174; -.
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   Amidation; Disulfide bond; Ion channel impairing toxin; Neurotoxin;
KW   Secreted; Signal; Toxin; Voltage-gated sodium channel impairing toxin.
FT   SIGNAL          <1..7
FT                   /evidence="ECO:0000250"
FT   CHAIN           8..71
FT                   /note="Toxin Td4"
FT                   /id="PRO_0000253767"
FT   DOMAIN          8..70
FT                   /note="LCN-type CS-alpha/beta"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU01210"
FT   MOD_RES         71
FT                   /note="Arginine amide"
FT                   /evidence="ECO:0000250"
FT   DISULFID        18..69
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU01210"
FT   DISULFID        22..44
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU01210"
FT   DISULFID        30..50
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU01210"
FT   DISULFID        34..52
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU01210"
FT   NON_TER         1
SQ   SEQUENCE   73 AA;  8293 MW;  95919AFE9FC8390F CRC64;
     IGMVVECKDG YLVGNDGCKY SCFTRPGTYC ANECSRVKGK DGYCYAWMAC YCYSMPNWVK
     TWDRATNRCG RGK