ID   SCX3_LEIQU              Reviewed;          64 AA.
AC   P01487;
DT   21-JUL-1986, integrated into UniProtKB/Swiss-Prot.
DT   01-NOV-1995, sequence version 2.
DT   03-AUG-2022, entry version 109.
DE   RecName: Full=Alpha-insect toxin Lqq3;
DE   AltName: Full=Lqq III;
DE            Short=LqqIII;
OS   Leiurus quinquestriatus quinquestriatus (Egyptian scorpion) (Deathstalker
OS   scorpion).
OC   Eukaryota; Metazoa; Ecdysozoa; Arthropoda; Chelicerata; Arachnida;
OC   Scorpiones; Buthida; Buthoidea; Buthidae; Leiurus.
OX   NCBI_TaxID=6885;
RN   [1]
RP   PROTEIN SEQUENCE.
RC   TISSUE=Venom;
RX   PubMed=8167952; DOI=10.1002/nt.2620010510;
RA   Kopeyan C., Mansuelle P., Martin-Eauclaire M.-F., Rochat H., Miranda F.;
RT   "Characterization of toxin III of the scorpion Leiurus quinquestriatus
RT   quinquestriatus: a new type of alpha-toxin highly toxic both to mammals and
RT   insects.";
RL   Nat. Toxins 1:308-312(1993).
RN   [2]
RP   PROTEIN SEQUENCE OF 1-26.
RC   TISSUE=Venom;
RX   PubMed=11945430; DOI=10.1016/0014-5793(70)80470-7;
RA   Rochat H., Rochat C., Kupeyan C., Miranda F., Lissitzky S., Edman P.;
RT   "Scorpion neurotoxins: a family of homologous proteins.";
RL   FEBS Lett. 10:349-351(1970).
RN   [3]
RP   STRUCTURE BY NMR, AND DISULFIDE BONDS.
RX   PubMed=8612608; DOI=10.1111/j.1432-1033.1996.00395.x;
RA   Landon C., Cornet B., Bonmatin J.-M., Kopeyan C., Rochat H., Vovelle F.,
RA   Ptak M.;
RT   "1H-NMR-derived secondary structure and the overall fold of the potent
RT   anti-mammal and anti-insect toxin III from the scorpion Leiurus
RT   quinquestriatus quinquestriatus.";
RL   Eur. J. Biochem. 236:395-404(1996).
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 contractive toxin is
CC       highly toxic both to mammals and insects.
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 50 ug/kg by subcutaneous injection in mouse, 60
CC       ng/g in Blattella germanica and 120 ng/g in Musca domestica.
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   PIR; A01747; NTSR3L.
DR   PDB; 1LQQ; NMR; -; A=1-64.
DR   PDBsum; 1LQQ; -.
DR   AlphaFoldDB; P01487; -.
DR   SMR; P01487; -.
DR   EvolutionaryTrace; P01487; -.
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-insect toxin Lqq3"
FT                   /id="PRO_0000066780"
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:8612608"
FT   DISULFID        16..36
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU01210,
FT                   ECO:0000269|PubMed:8612608"
FT   DISULFID        22..46
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU01210,
FT                   ECO:0000269|PubMed:8612608"
FT   DISULFID        26..48
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU01210,
FT                   ECO:0000269|PubMed:8612608"
FT   STRAND          2..5
FT                   /evidence="ECO:0007829|PDB:1LQQ"
FT   STRAND          8..11
FT                   /evidence="ECO:0007829|PDB:1LQQ"
FT   HELIX           19..28
FT                   /evidence="ECO:0007829|PDB:1LQQ"
FT   STRAND          32..38
FT                   /evidence="ECO:0007829|PDB:1LQQ"
FT   STRAND          44..51
FT                   /evidence="ECO:0007829|PDB:1LQQ"
FT   STRAND          53..55
FT                   /evidence="ECO:0007829|PDB:1LQQ"
FT   STRAND          60..62
FT                   /evidence="ECO:0007829|PDB:1LQQ"
SQ   SEQUENCE   64 AA;  7240 MW;  205171E0C0512753 CRC64;
     VRDAYIAKNY NCVYECFRDS YCNDLCTKNG ASSGYCQWAG KYGNACWCYA LPDNVPIRVP
     GKCH