ID   3S1B_NAJKA              Reviewed;          61 AA.
AC   P59275;
DT   12-FEB-2003, integrated into UniProtKB/Swiss-Prot.
DT   12-FEB-2003, sequence version 1.
DT   25-MAY-2022, entry version 73.
DE   RecName: Full=Cobrotoxin-b {ECO:0000303|PubMed:12039691};
DE            Short=CBT-b {ECO:0000303|PubMed:12039691};
DE   AltName: Full=Short neurotoxin III {ECO:0000303|PubMed:11904231};
DE            Short=NT3 {ECO:0000303|PubMed:11904231};
OS   Naja kaouthia (Monocled cobra) (Naja siamensis).
OC   Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi;
OC   Lepidosauria; Squamata; Bifurcata; Unidentata; Episquamata; Toxicofera;
OC   Serpentes; Colubroidea; Elapidae; Elapinae; Naja.
OX   NCBI_TaxID=8649;
RN   [1]
RP   PROTEIN SEQUENCE, TOXIC DOSE, AND SUBCELLULAR LOCATION.
RC   TISSUE=Venom;
RX   PubMed=12039691; DOI=10.1016/s1532-0456(02)00049-2;
RA   Meng Q.-X., Wang W.-Y., Lu Q.-M., Jin Y., Wei J.-F., Zhu S.-W.,
RA   Xiong Y.-L.;
RT   "A novel short neurotoxin, cobrotoxin c, from monocellate cobra (Naja
RT   kaouthia) venom: isolation and purification, primary and secondary
RT   structure determination, and tertiary structure modeling.";
RL   Comp. Biochem. Physiol. 132C:113-121(2002).
RN   [2]
RP   INHIBITORY CONCENTRATION.
RX   PubMed=11904231; DOI=10.1016/s0167-4838(01)00326-0;
RA   Cheng Y., Meng Q.-X., Wang W.-Y., Wang J.;
RT   "Structure-function relationship of three neurotoxins from the venom of
RT   Naja kaouthia: a comparison between the NMR-derived structure of NT2 with
RT   its homologues, NT1 and NT3.";
RL   Biochim. Biophys. Acta 1594:353-363(2002).
CC   -!- FUNCTION: Produces peripheral paralysis by blocking neuromuscular
CC       transmission at the postsynaptic site. Binds to the nicotinic
CC       acetylcholine receptor. {ECO:0000269|PubMed:12039691,
CC       ECO:0000305|PubMed:12039691}.
CC   -!- SUBCELLULAR LOCATION: Secreted {ECO:0000269|PubMed:12039691}.
CC   -!- TISSUE SPECIFICITY: Expressed by the venom gland. {ECO:0000305}.
CC   -!- TOXIC DOSE: LD(50) is 400 mg/kg by intraperitoneal injection into mice.
CC       {ECO:0000269|PubMed:12039691}.
CC   -!- MISCELLANEOUS: It inhibits muscle contraction with an IC(50) of 0.23
CC       ug/ml. {ECO:0000269|PubMed:11904231}.
CC   -!- SIMILARITY: Belongs to the snake three-finger toxin family. Short-chain
CC       subfamily. Type I alpha-neurotoxin sub-subfamily. {ECO:0000305}.
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DR   AlphaFoldDB; P59275; -.
DR   SMR; P59275; -.
DR   GO; GO:0005576; C:extracellular region; IEA:UniProtKB-SubCell.
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   Direct protein sequencing; Disulfide bond; Ion channel impairing toxin;
KW   Neurotoxin; Postsynaptic neurotoxin; Secreted; Toxin.
FT   CHAIN           1..61
FT                   /note="Cobrotoxin-b"
FT                   /evidence="ECO:0000269|PubMed:12039691"
FT                   /id="PRO_0000093592"
FT   SITE            56
FT                   /note="May be the main cause for the toxicity difference
FT                   between this toxin and cobrotoxin-c"
FT   DISULFID        3..23
FT                   /evidence="ECO:0000250|UniProtKB:P0C1Z0"
FT   DISULFID        17..40
FT                   /evidence="ECO:0000250|UniProtKB:P0C1Z0"
FT   DISULFID        42..53
FT                   /evidence="ECO:0000250|UniProtKB:P0C1Z0"
FT   DISULFID        54..59
FT                   /evidence="ECO:0000250|UniProtKB:P0C1Z0"
SQ   SEQUENCE   61 AA;  6944 MW;  74A0F0C1EF499961 CRC64;
     LECHNQQSSQ TPTTKTCSGE TNCYKKWWSD HRGTIIERGC GCPKVKPGVN LNCCRRDRCN
     N