ID   3LK3_BUNMU              Reviewed;          87 AA.
AC   P15817; P87353;
DT   01-APR-1990, integrated into UniProtKB/Swiss-Prot.
DT   01-APR-1990, sequence version 1.
DT   25-MAY-2022, entry version 104.
DE   RecName: Full=Kappa-3-bungarotoxin {ECO:0000303|PubMed:2322821};
DE            Short=K3Bgt {ECO:0000303|PubMed:2322821};
DE   AltName: Full=Kappa-neurotoxin;
DE   AltName: Full=Long neurotoxin CR1;
DE   Flags: Precursor;
OS   Bungarus multicinctus (Many-banded krait).
OC   Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi;
OC   Lepidosauria; Squamata; Bifurcata; Unidentata; Episquamata; Toxicofera;
OC   Serpentes; Colubroidea; Elapidae; Bungarinae; Bungarus.
OX   NCBI_TaxID=8616;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RC   TISSUE=Venom gland;
RX   PubMed=2315018; DOI=10.1093/nar/18.4.1050;
RA   Danse J.-M., Garnier J.-M.;
RT   "cDNA deduced amino-acid sequences of two novel kappa-neurotoxins from
RT   Bungarus multicinctus.";
RL   Nucleic Acids Res. 18:1050-1050(1990).
RN   [2]
RP   NUCLEOTIDE SEQUENCE [MRNA].
RC   TISSUE=Liver;
RX   PubMed=12403176; DOI=10.1023/a:1020139728292;
RA   Chang L.-S., Chung C., Lin J., Hong E.;
RT   "Organization and phylogenetic analysis of kappa-bungarotoxin genes from
RT   Bungarus multicinctus (Taiwan banded krait).";
RL   Genetica 115:213-221(2002).
RN   [3]
RP   PROTEIN SEQUENCE OF 23-67, FUNCTION, SUBCELLULAR LOCATION, AND SUBUNIT.
RC   TISSUE=Venom;
RX   PubMed=2322821; DOI=10.1016/0006-8993(90)90548-p;
RA   Chiappinelli V.A., Wolf K.M., Grant G.A., Chen S.-J.;
RT   "Kappa 2-bungarotoxin and kappa 3-bungarotoxin: two new neuronal nicotinic
RT   receptor antagonists isolated from the venom of Bungarus multicinctus.";
RL   Brain Res. 509:237-248(1990).
CC   -!- FUNCTION: Postsynaptic neurotoxin that binds and inhibits neuronal
CC       nicotinic acetylcholine receptors (nAChR) with high affinity
CC       (IC(50)<100 nM). Is a selective, and slowly reversible antagonist of
CC       alpha-3/CHRNA3-containing and some alpha-4/CHRNA4-containing AChRs.
CC       {ECO:0000250|UniProtKB:P01398, ECO:0000269|PubMed:2322821}.
CC   -!- SUBUNIT: Homodimer and heterodimer with kappa 2-bungarotoxin; non-
CC       covalently-linked. {ECO:0000269|PubMed:2322821}.
CC   -!- SUBCELLULAR LOCATION: Secreted {ECO:0000269|PubMed:2322821}.
CC   -!- TISSUE SPECIFICITY: Expressed by the venom gland. {ECO:0000305}.
CC   -!- SIMILARITY: Belongs to the snake three-finger toxin family. Long-chain
CC       subfamily. Kappa-neurotoxin sub-subfamily. {ECO:0000305}.
CC   -!- CAUTION: The nucleotide sequence submitted as Y11769 is a genomic DNA
CC       sequence and not a mRNA sequence, as mentioned in the submission.
CC       {ECO:0000305|PubMed:12403176}.
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DR   EMBL; X51413; CAA35775.1; -; mRNA.
DR   EMBL; Y11769; CAA72434.1; -; mRNA.
DR   PIR; S08398; B60549.
DR   AlphaFoldDB; P15817; -.
DR   SMR; P15817; -.
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; Signal; Toxin.
FT   SIGNAL          1..21
FT   CHAIN           22..87
FT                   /note="Kappa-3-bungarotoxin"
FT                   /id="PRO_0000035412"
FT   DISULFID        24..42
FT                   /evidence="ECO:0000250|UniProtKB:P01398"
FT   DISULFID        35..63
FT                   /evidence="ECO:0000250|UniProtKB:P01398"
FT   DISULFID        48..52
FT                   /evidence="ECO:0000250|UniProtKB:P01398"
FT   DISULFID        67..79
FT                   /evidence="ECO:0000250|UniProtKB:P01398"
FT   DISULFID        80..85
FT                   /evidence="ECO:0000250|UniProtKB:P01398"
FT   CONFLICT        7
FT                   /note="S -> T (in Ref. 2; CAA72434)"
FT                   /evidence="ECO:0000305"
SQ   SEQUENCE   87 AA;  9660 MW;  A084F400EFE6BB66 CRC64;
     MKTLLLSLVV VTIVCLDLGY TRTCLISPSS TPQTCPNGQD ICFRKAQCDN FCHSRGPVIE
     QGCVATCPQF RSNYRSLLCC RTDNCNH