ID   SCX8_MESMA              Reviewed;          64 AA.
AC   P54135;
DT   01-OCT-1996, integrated into UniProtKB/Swiss-Prot.
DT   01-OCT-1996, sequence version 1.
DT   03-AUG-2022, entry version 106.
DE   RecName: Full=Alpha-mammal toxin BmK-M8;
DE            Short=BmK8;
DE            Short=Bmk M8;
DE   AltName: Full=BmK-VIII;
DE            Short=BmKVIII;
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   PROTEIN SEQUENCE, X-RAY CRYSTALLOGRAPHY (1.85 ANGSTROMS), DISULFIDE BONDS,
RP   AND TOXIC DOSE.
RX   PubMed=8780783; DOI=10.1006/jmbi.1996.0473;
RA   Li H.-M., Wang D.-C., Zeng Z.-H., Jin L., Hu R.-Q.;
RT   "Crystal structure of an acidic neurotoxin from scorpion Buthus martensii
RT   Karsch at 1.85-A resolution.";
RL   J. Mol. Biol. 261:415-431(1996).
RN   [2]
RP   CRYSTALLIZATION.
RC   TISSUE=Venom;
RX   PubMed=10089445; DOI=10.1107/s0907444998006593;
RA   Li H.-M., Zhao T., Jin L., Wang M., Zhang Y., Wang D.-C.;
RT   "A series of bioactivity-variant neurotoxins from scorpion Buthus martensii
RT   Karsch: purification, crystallization and crystallographic analysis.";
RL   Acta Crystallogr. D 55:341-344(1999).
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 acidic toxin has a weak
CC       toxicity and is active against 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   -!- TOXIC DOSE: LD(50) is 10 mg/kg by intravenous injection into mice.
CC       {ECO:0000269|PubMed:8780783}.
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   PDB; 1SNB; X-ray; 1.90 A; A=1-64.
DR   PDBsum; 1SNB; -.
DR   AlphaFoldDB; P54135; -.
DR   SMR; P54135; -.
DR   EvolutionaryTrace; P54135; -.
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   3D-structure; Direct protein sequencing; Disulfide bond;
KW   Ion channel impairing toxin; Neurotoxin; Secreted; Toxin;
KW   Voltage-gated sodium channel impairing toxin.
FT   CHAIN           1..64
FT                   /note="Alpha-mammal toxin BmK-M8"
FT                   /id="PRO_0000066753"
FT   DOMAIN          2..64
FT                   /note="LCN-type CS-alpha/beta"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU01210"
FT   DISULFID        12..63
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU01210,
FT                   ECO:0000269|PubMed:8780783"
FT   DISULFID        16..36
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU01210,
FT                   ECO:0000269|PubMed:8780783"
FT   DISULFID        22..46
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU01210,
FT                   ECO:0000269|PubMed:8780783"
FT   DISULFID        26..48
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU01210,
FT                   ECO:0000269|PubMed:8780783"
FT   STRAND          2..6
FT                   /evidence="ECO:0007829|PDB:1SNB"
FT   HELIX           19..28
FT                   /evidence="ECO:0007829|PDB:1SNB"
FT   STRAND          32..40
FT                   /evidence="ECO:0007829|PDB:1SNB"
FT   STRAND          43..51
FT                   /evidence="ECO:0007829|PDB:1SNB"
SQ   SEQUENCE   64 AA;  6961 MW;  48B3144B1C374568 CRC64;
     GRDAYIADSE NCTYFCGSNP YCNDVCTENG AKSGYCQWAG RYGNACYCID LPASERIKEP
     GKCG