ID   3L23_NAJNA              Reviewed;          71 AA.
AC   P25671;
DT   01-MAY-1992, integrated into UniProtKB/Swiss-Prot.
DT   01-MAY-1992, sequence version 1.
DT   03-AUG-2022, entry version 103.
DE   RecName: Full=Long neurotoxin 3;
DE   AltName: Full=Toxin C {ECO:0000303|Ref.1};
OS   Naja naja (Indian cobra).
OC   Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi;
OC   Lepidosauria; Squamata; Bifurcata; Unidentata; Episquamata; Toxicofera;
OC   Serpentes; Colubroidea; Elapidae; Elapinae; Naja.
OX   NCBI_TaxID=35670;
RN   [1]
RP   PROTEIN SEQUENCE, TOXIC DOSE, AND SUBCELLULAR LOCATION.
RC   TISSUE=Venom;
RA   Ohta M., Sasaki T., Hayashi K.;
RT   "The primary structure of toxin C from the venom of the Indian cobra (Naja
RT   naja).";
RL   Chem. Pharm. Bull. 29:1458-1475(1981).
RN   [2]
RP   X-RAY CRYSTALLOGRAPHY (2.4 ANGSTROMS), AND DISULFIDE BONDS.
RX   PubMed=1939183; DOI=10.2210/pdb2ctx/pdb;
RA   Betzel C., Lange G., Pal G.P., Wilson K.S., Maelicke A., Saenger W.;
RT   "The refined crystal structure of alpha-cobratoxin from Naja naja siamensis
RT   at 2.4-A resolution.";
RL   J. Biol. Chem. 266:21530-21536(1991).
CC   -!- FUNCTION: Binds with high affinity to muscular (alpha-1/CHRNA1) and
CC       neuronal (alpha-7/CHRNA7) nicotinic acetylcholine receptor (nAChR) and
CC       inhibits acetylcholine from binding to the receptor, thereby impairing
CC       neuromuscular and neuronal transmission.
CC       {ECO:0000250|UniProtKB:P60615}.
CC   -!- SUBCELLULAR LOCATION: Secreted {ECO:0000269|Ref.1}.
CC   -!- TISSUE SPECIFICITY: Expressed by the venom gland. {ECO:0000305|Ref.1}.
CC   -!- TOXIC DOSE: LD(50) is 0.10 to 0.15 mg/kg by subcutaneous injection.
CC       {ECO:0000269|Ref.1}.
CC   -!- SIMILARITY: Belongs to the snake three-finger toxin family. Long-chain
CC       subfamily. Type II alpha-neurotoxin sub-subfamily. {ECO:0000305}.
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DR   PDB; 2CTX; X-ray; 2.40 A; A=1-71.
DR   PDBsum; 2CTX; -.
DR   AlphaFoldDB; P25671; -.
DR   SMR; P25671; -.
DR   EvolutionaryTrace; P25671; -.
DR   Proteomes; UP000694559; Unplaced.
DR   GO; GO:0005576; C:extracellular region; IEA:UniProtKB-SubCell.
DR   GO; GO:0030550; F:acetylcholine receptor inhibitor activity; IEA:UniProtKB-KW.
DR   GO; GO:0099106; F:ion channel regulator activity; IEA:UniProtKB-KW.
DR   GO; GO:0090729; F:toxin activity; IEA:UniProtKB-KW.
DR   CDD; cd00206; snake_toxin; 1.
DR   Gene3D; 2.10.60.10; -; 1.
DR   InterPro; IPR003571; Snake_3FTx.
DR   InterPro; IPR045860; Snake_toxin-like_sf.
DR   InterPro; IPR018354; Snake_toxin_con_site.
DR   SUPFAM; SSF57302; SSF57302; 1.
DR   PROSITE; PS00272; SNAKE_TOXIN; 1.
PE   1: Evidence at protein level;
KW   3D-structure; Acetylcholine receptor inhibiting toxin;
KW   Direct protein sequencing; Disulfide bond; Ion channel impairing toxin;
KW   Neurotoxin; Postsynaptic neurotoxin; Reference proteome; Secreted; Toxin.
FT   CHAIN           1..71
FT                   /note="Long neurotoxin 3"
FT                   /evidence="ECO:0000269|Ref.1"
FT                   /id="PRO_0000093549"
FT   DISULFID        3..20
FT                   /evidence="ECO:0000269|PubMed:1939183,
FT                   ECO:0007744|PDB:2CTX"
FT   DISULFID        14..41
FT                   /evidence="ECO:0000269|PubMed:1939183,
FT                   ECO:0007744|PDB:2CTX"
FT   DISULFID        26..30
FT                   /evidence="ECO:0000269|PubMed:1939183,
FT                   ECO:0007744|PDB:2CTX"
FT   DISULFID        45..56
FT                   /evidence="ECO:0000269|PubMed:1939183,
FT                   ECO:0007744|PDB:2CTX"
FT   DISULFID        57..62
FT                   /evidence="ECO:0000269|PubMed:1939183,
FT                   ECO:0007744|PDB:2CTX"
FT   STRAND          2..4
FT                   /evidence="ECO:0007829|PDB:2CTX"
FT   STRAND          10..13
FT                   /evidence="ECO:0007829|PDB:2CTX"
FT   STRAND          19..25
FT                   /evidence="ECO:0007829|PDB:2CTX"
FT   TURN            28..32
FT                   /evidence="ECO:0007829|PDB:2CTX"
FT   STRAND          36..44
FT                   /evidence="ECO:0007829|PDB:2CTX"
FT   STRAND          53..57
FT                   /evidence="ECO:0007829|PDB:2CTX"
FT   STRAND          67..69
FT                   /evidence="ECO:0007829|PDB:2CTX"
SQ   SEQUENCE   71 AA;  7833 MW;  67A5A57A85E9AC33 CRC64;
     IRCFITPDIT SKDCPNGHVC YTKTWCDAFC SIRGKRVDLG CAATCPTVKT GVDIQCCSTD
     DCDPFPTRKR P