ID   3L22_HYDST              Reviewed;          72 AA.
AC   P01381;
DT   21-JUL-1986, integrated into UniProtKB/Swiss-Prot.
DT   21-JUL-1986, sequence version 1.
DT   25-MAY-2022, entry version 95.
DE   RecName: Full=Alpha-elapitoxin-Ast2b;
DE            Short=Alpha-EPTX-Ast2b;
DE   AltName: Full=Long neurotoxin 2;
DE   AltName: Full=Toxin C;
OS   Hydrophis stokesii (Stokes's sea snake) (Astrotia stokesii).
OC   Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi;
OC   Lepidosauria; Squamata; Bifurcata; Unidentata; Episquamata; Toxicofera;
OC   Serpentes; Colubroidea; Hydrophiidae; Hydrophis.
OX   NCBI_TaxID=355677;
RN   [1]
RP   PROTEIN SEQUENCE, AMIDATION AT ARG-72, TOXIC DOSE, AND SUBCELLULAR
RP   LOCATION.
RC   TISSUE=Venom;
RX   PubMed=743209; DOI=10.1042/bj1750507;
RA   Maeda N., Tamiya N.;
RT   "Three neurotoxins from the venom of a sea snake Astrotia stokesii,
RT   including two long-chain neurotoxic proteins with amidated C-termini.";
RL   Biochem. J. 175:507-517(1978).
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|PubMed:743209}.
CC   -!- TISSUE SPECIFICITY: Expressed by the venom gland. {ECO:0000305}.
CC   -!- TOXIC DOSE: LD(50) is 0.096 mg/kg by intramuscular injection into mice.
CC       {ECO:0000269|PubMed:743209}.
CC   -!- SIMILARITY: Belongs to the snake three-finger toxin family. Long-chain
CC       subfamily. Type II alpha-neurotoxin sub-subfamily. {ECO:0000305}.
CC   ---------------------------------------------------------------------------
CC   Copyrighted by the UniProt Consortium, see https://www.uniprot.org/terms
CC   Distributed under the Creative Commons Attribution (CC BY 4.0) License
CC   ---------------------------------------------------------------------------
DR   PIR; A01652; N2AT2.
DR   AlphaFoldDB; P01381; -.
DR   SMR; P01381; -.
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   1: Evidence at protein level;
KW   Acetylcholine receptor inhibiting toxin; Amidation;
KW   Direct protein sequencing; Disulfide bond; Ion channel impairing toxin;
KW   Neurotoxin; Postsynaptic neurotoxin; Secreted; Toxin.
FT   CHAIN           1..72
FT                   /note="Alpha-elapitoxin-Ast2b"
FT                   /id="PRO_0000093531"
FT   MOD_RES         72
FT                   /note="Arginine amide"
FT                   /evidence="ECO:0000269|PubMed:743209"
FT   DISULFID        3..20
FT                   /evidence="ECO:0000250"
FT   DISULFID        13..41
FT                   /evidence="ECO:0000250"
FT   DISULFID        26..30
FT                   /evidence="ECO:0000250"
FT   DISULFID        45..56
FT                   /evidence="ECO:0000250"
FT   DISULFID        57..62
FT                   /evidence="ECO:0000250"
SQ   SEQUENCE   72 AA;  7790 MW;  8334C88BD20873AC CRC64;
     LSCYLGYKHS QTCPPGENVC FVKTWCDAFC STRGERIVMG CAATCPTAKS GVHIACCSTD
     NCNIYTKWGS GR