ID   SCA4_MESMA              Reviewed;          85 AA.
AC   Q4TUA4;
DT   31-OCT-2006, integrated into UniProtKB/Swiss-Prot.
DT   19-JUL-2005, sequence version 1.
DT   03-AUG-2022, entry version 47.
DE   RecName: Full=Alpha-toxin 4;
DE   AltName: Full=BmK alpha IV;
DE   AltName: Full=BmKalpha4;
DE   Flags: Precursor;
OS   Mesobuthus martensii (Manchurian scorpion) (Buthus martensii).
OC   Eukaryota; Metazoa; Ecdysozoa; Arthropoda; Chelicerata; Arachnida;
OC   Scorpiones; Buthida; Buthoidea; Buthidae; Mesobuthus.
OX   NCBI_TaxID=34649;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [MRNA], PROTEIN SEQUENCE OF 20-27, TOXIC DOSE, AND MASS
RP   SPECTROMETRY.
RC   TISSUE=Venom, and Venom gland;
RX   PubMed=16800812; DOI=10.1042/bj20060035;
RA   Chai Z.-F., Zhu M.-M., Bai Z.-T., Liu T., Tan M., Pang X.-Y., Ji Y.-H.;
RT   "BmK alphaIV, a novel modulator of sodium channels: from genomic
RT   organization to functional analysis.";
RL   Biochem. J. 399:445-453(2006).
CC   -!- FUNCTION: Alpha toxins bind voltage-independently at site-3 of sodium
CC       channels (Nav) and inhibit the inactivation of the activated channels,
CC       thereby blocking neuronal transmission. This toxin is active against
CC       insects and mammals.
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=7733.59; Method=MALDI;
CC       Evidence={ECO:0000269|PubMed:16800812};
CC   -!- TOXIC DOSE: LD(50) is 10.4 ug/kg by intracerebroventricular injection
CC       into mice and is 4.7 ug/g to cockroaches.
CC       {ECO:0000269|PubMed:16800812}.
CC   -!- SIMILARITY: Belongs to the long (4 C-C) scorpion toxin superfamily.
CC       Sodium channel inhibitor family. Alpha subfamily. {ECO:0000305}.
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DR   EMBL; DQ058408; AAY56791.1; -; Genomic_DNA.
DR   AlphaFoldDB; Q4TUA4; -.
DR   SMR; Q4TUA4; -.
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   CDD; cd00107; Knot1; 1.
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; Signal; Toxin;
KW   Voltage-gated sodium channel impairing toxin.
FT   SIGNAL          1..19
FT                   /evidence="ECO:0000269|PubMed:16800812"
FT   CHAIN           20..85
FT                   /note="Alpha-toxin 4"
FT                   /id="PRO_0000257746"
FT   DOMAIN          21..83
FT                   /note="LCN-type CS-alpha/beta"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU01210"
FT   DISULFID        31..82
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU01210"
FT   DISULFID        35..55
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU01210"
FT   DISULFID        41..65
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU01210"
FT   DISULFID        45..67
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU01210"
SQ   SEQUENCE   85 AA;  9454 MW;  6EFC463E15D95091 CRC64;
     MNYLVFFSLA LLLMTGVESV RDGYIADDKN CAYFCGRNAY CDDECKKKGA ESGYCQWAGV
     YGNACWCYKL PDKVPIRVPG RCNGG