ID   3L2N3_BUNCA             Reviewed;          73 AA.
AC   P85140;
DT   15-MAY-2007, integrated into UniProtKB/Swiss-Prot.
DT   19-JAN-2010, sequence version 2.
DT   25-MAY-2022, entry version 50.
DE   RecName: Full=Alpha-bungarotoxin N3 {ECO:0000250|UniProtKB:P60615, ECO:0000303|PubMed:19728988};
DE            Short=AlphaN3 {ECO:0000303|PubMed:19728988};
OS   Bungarus candidus (Malayan krait).
OC   Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi;
OC   Lepidosauria; Squamata; Bifurcata; Unidentata; Episquamata; Toxicofera;
OC   Serpentes; Colubroidea; Elapidae; Bungarinae; Bungarus.
OX   NCBI_TaxID=92438;
RN   [1]
RP   PROTEIN SEQUENCE, FUNCTION, SUBCELLULAR LOCATION, AND TOXIC DOSE.
RC   TISSUE=Venom;
RX   PubMed=19728988; DOI=10.1016/j.bbrc.2009.08.145;
RA   Karsani S.A., Othman I.;
RT   "Isolation, complete amino acid sequence and characterization of a
RT   previously unreported post-synaptic neurotoxin - AlphaN3, from the venom of
RT   Bungarus candidus.";
RL   Biochem. Biophys. Res. Commun. 389:343-348(2009).
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 (By similarity). Mice injected
CC       with this toxin develop flaccid paralysis followed by death.
CC       Irreversibly inhibits twitches in a concentration-dependent manner in
CC       rat phrenic nerve-hemidiaphragm and chick biventer cervicis muscle
CC       (PubMed:19728988). {ECO:0000250|UniProtKB:P60615,
CC       ECO:0000269|PubMed:19728988}.
CC   -!- SUBUNIT: Monomer in solution, homodimer in crystal state.
CC       {ECO:0000250|UniProtKB:P60615}.
CC   -!- SUBCELLULAR LOCATION: Secreted {ECO:0000269|PubMed:19728988}.
CC   -!- TISSUE SPECIFICITY: Expressed by the venom gland. {ECO:0000305}.
CC   -!- TOXIC DOSE: LD(50) is 0.16 ug/g by intravenous injection into mice.
CC       {ECO:0000269|PubMed:19728988}.
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   AlphaFoldDB; P85140; -.
DR   SMR; P85140; -.
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   Acetylcholine receptor inhibiting toxin; Direct protein sequencing;
KW   Disulfide bond; Ion channel impairing toxin; Neurotoxin;
KW   Postsynaptic neurotoxin; Secreted; Toxin.
FT   CHAIN           1..73
FT                   /note="Alpha-bungarotoxin N3"
FT                   /id="PRO_0000287679"
FT   DISULFID        3..23
FT                   /evidence="ECO:0000250|UniProtKB:P60615"
FT   DISULFID        16..43
FT                   /evidence="ECO:0000250|UniProtKB:P60615"
FT   DISULFID        28..32
FT                   /evidence="ECO:0000250|UniProtKB:P60615"
FT   DISULFID        47..58
FT                   /evidence="ECO:0000250|UniProtKB:P60615"
FT   DISULFID        59..64
FT                   /evidence="ECO:0000250|UniProtKB:P60615"
SQ   SEQUENCE   73 AA;  7787 MW;  3C80654AEB494078 CRC64;
     IVCHTTATSP ISAVTCPPGE NLCYRKMCDA ICSSRGKVVE LGCAATCPSK KPYEEVTCCS
     NDKCNPHPKQ RPG