ID   SCM2_MESMA              Reviewed;          64 AA.
AC   P58488;
DT   19-DEC-2001, integrated into UniProtKB/Swiss-Prot.
DT   19-DEC-2001, sequence version 1.
DT   03-AUG-2022, entry version 81.
DE   RecName: Full=Alpha-like toxin BmK M2 {ECO:0000303|PubMed:10666623};
DE            Short=BmK-M2;
DE            Short=BmKM2;
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   X-RAY CRYSTALLOGRAPHY (1.76 ANGSTROMS), FUNCTION, SUBCELLULAR LOCATION,
RP   DISULFIDE BOND, AND TOXIC DOSE.
RC   TISSUE=Venom;
RX   PubMed=10666623; DOI=10.1107/s0907444999014614;
RA   He X.-L., Deng J.P., Wang M., Zhang Y., Wang D.-C.;
RT   "Structure of a new neurotoxin from the scorpion Buthus martensii Karsch at
RT   1.76 A.";
RL   Acta Crystallogr. D 56:25-33(2000).
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       both mammals and insects, and is classified as an alpha-like toxin.
CC       {ECO:0000305|PubMed:10666623}.
CC   -!- SUBCELLULAR LOCATION: Secreted {ECO:0000269|PubMed:10666623}.
CC   -!- TISSUE SPECIFICITY: Expressed by the venom gland.
CC       {ECO:0000305|PubMed:10666623}.
CC   -!- DOMAIN: Has the structural arrangement of an alpha-helix connected to
CC       antiparallel beta-sheets by disulfide bonds (CS-alpha/beta).
CC       {ECO:0000269|PubMed:10666623}.
CC   -!- TOXIC DOSE: LD(50) is 0.5 mg/kg in mouse (PubMed:10666623).
CC       {ECO:0000305|PubMed:10666623}.
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; 1CHZ; X-ray; 1.76 A; A=1-64.
DR   PDBsum; 1CHZ; -.
DR   AlphaFoldDB; P58488; -.
DR   SMR; P58488; -.
DR   EvolutionaryTrace; P58488; -.
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; Disulfide bond; Ion channel impairing toxin; Neurotoxin;
KW   Secreted; Toxin; Voltage-gated sodium channel impairing toxin.
FT   CHAIN           1..64
FT                   /note="Alpha-like toxin BmK M2"
FT                   /evidence="ECO:0000269|PubMed:10666623"
FT                   /id="PRO_0000066749"
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:0000269|PubMed:10666623,
FT                   ECO:0000312|PDB:1CHZ"
FT   DISULFID        16..36
FT                   /evidence="ECO:0000269|PubMed:10666623,
FT                   ECO:0000312|PDB:1CHZ"
FT   DISULFID        22..46
FT                   /evidence="ECO:0000269|PubMed:10666623,
FT                   ECO:0000312|PDB:1CHZ"
FT   DISULFID        26..48
FT                   /evidence="ECO:0000269|PubMed:10666623,
FT                   ECO:0000312|PDB:1CHZ"
FT   STRAND          2..8
FT                   /evidence="ECO:0007829|PDB:1CHZ"
FT   TURN            9..11
FT                   /evidence="ECO:0007829|PDB:1CHZ"
FT   HELIX           19..28
FT                   /evidence="ECO:0007829|PDB:1CHZ"
FT   STRAND          32..40
FT                   /evidence="ECO:0007829|PDB:1CHZ"
FT   STRAND          43..51
FT                   /evidence="ECO:0007829|PDB:1CHZ"
SQ   SEQUENCE   64 AA;  7212 MW;  8DF2869A098AD864 CRC64;
     VRDAYIAKPH NCVYECARNE YCNNLCTKNG AKSGYCQWSG KYGNGCWCIE LPDNVPIRVP
     GKCH