ID   3L23_BUNCA              Reviewed;          75 AA.
AC   A1IVR7;
DT   03-MAY-2011, integrated into UniProtKB/Swiss-Prot.
DT   06-FEB-2007, sequence version 1.
DT   25-MAY-2022, entry version 58.
DE   RecName: Full=Alpha-elapitoxin-Bc2c {ECO:0000305};
DE            Short=Alpha-EPTX-Bc2c {ECO:0000305};
DE   AltName: Full=Alpha-delta-Bgt-3 {ECO:0000312|EMBL:CAJ77818.1};
DE   AltName: Full=Alpha/delta-bungarotoxin-3 {ECO:0000303|PubMed:30944155};
DE            Short=Alpha/delta-BgTx-3 {ECO:0000303|PubMed:30944155};
DE   Flags: Precursor; Fragment;
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   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RC   TISSUE=Venom;
RX   PubMed=30944155; DOI=10.1042/bcj20180909;
RA   Utkin Y.N., Kuch U., Kasheverov I.E., Lebedev D.S., Cederlund E.,
RA   Molles B.E., Polyak I., Ivanov I.A., Prokopev N.A., Ziganshin R.H.,
RA   Jornvall H., Alvelius G., Chanhome L., Warrell D.A., Mebs D., Bergman T.,
RA   Tsetlin V.I.;
RT   "Novel long-chain neurotoxins from Bungarus candidus distinguish the two
RT   binding sites in muscle-type nicotinic acetylcholine receptors.";
RL   Biochem. J. 476:1285-1302(2019).
CC   -!- FUNCTION: Binds to muscular and neuronal nicotinic acetylcholine
CC       receptor (nAChR) and inhibits acetylcholine from binding to the
CC       receptor, thereby impairing neuromuscular and neuronal transmission (By
CC       similarity). Blocks muscle type nAChR (By similarity). Also binds with
CC       high affinity to alpha-7/CHRNA7 nAChRs (By similarity). In addition,
CC       shows a weak inhibition of neuronal alpha-3-beta-2/CHRNA3-CHRNB2 nAChR
CC       (By similarity). Selectively binds to alpha-1-delta subunit interface
CC       of the mouse muscle nicotinic acetylcholine receptor, with a 10-fold
CC       higher affinity for the adult than for the fetal receptors (By
CC       similarity). In vivo, when intraperitoneally injected into mice, causes
CC       flaccid paralysis and respiratory distress, followed by death within 2-
CC       4 hours (By similarity). {ECO:0000250|UniProtKB:A1IVR8}.
CC   -!- SUBUNIT: Monomer in solution, homodimer in crystal state.
CC       {ECO:0000250|UniProtKB:P60615}.
CC   -!- SUBCELLULAR LOCATION: Secreted {ECO:0000250|UniProtKB:A1IVR8}.
CC   -!- TISSUE SPECIFICITY: Expressed by the venom gland. {ECO:0000305}.
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   EMBL; AM231680; CAJ77818.1; -; Genomic_DNA.
DR   AlphaFoldDB; A1IVR7; -.
DR   SMR; A1IVR7; -.
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   InterPro; IPR035076; Toxin/TOLIP.
DR   Pfam; PF00087; Toxin_TOLIP; 1.
DR   SUPFAM; SSF57302; SSF57302; 1.
DR   PROSITE; PS00272; SNAKE_TOXIN; 1.
PE   3: Inferred from homology;
KW   Acetylcholine receptor inhibiting toxin; Disulfide bond;
KW   Ion channel impairing toxin; Neurotoxin; Postsynaptic neurotoxin; Secreted;
KW   Signal; Toxin.
FT   SIGNAL          <1..2
FT                   /evidence="ECO:0000250|UniProtKB:A1IVR8"
FT   CHAIN           3..75
FT                   /note="Alpha-elapitoxin-Bc2c"
FT                   /evidence="ECO:0000305|PubMed:30944155"
FT                   /id="PRO_5000189419"
FT   DISULFID        5..24
FT                   /evidence="ECO:0000250|UniProtKB:P60615"
FT   DISULFID        17..45
FT                   /evidence="ECO:0000250|UniProtKB:P60615"
FT   DISULFID        30..34
FT                   /evidence="ECO:0000250|UniProtKB:P60615"
FT   DISULFID        49..60
FT                   /evidence="ECO:0000250|UniProtKB:P60615"
FT   DISULFID        61..66
FT                   /evidence="ECO:0000250|UniProtKB:P60615"
FT   NON_TER         1
FT                   /evidence="ECO:0000312|EMBL:CAJ77818.1"
SQ   SEQUENCE   75 AA;  8350 MW;  9166C63B2B24240B CRC64;
     YTLLCYKTPS PINAETCPPG ENLCYTKMWC DAWCSSRGKV VELGCAATCP SKKPYEEVTC
     CSTDKCNPHP KQRPD