ID   TX34B_PHONI             Reviewed;         115 AA.
AC   O76198;
DT   23-JAN-2002, integrated into UniProtKB/Swiss-Prot.
DT   01-NOV-1998, sequence version 1.
DT   25-MAY-2022, entry version 58.
DE   RecName: Full=U2-ctenitoxin-Pn1b;
DE            Short=U2-CNTX-Pn1b;
DE   AltName: Full=Neurotoxin Pn2-1A;
DE   Flags: Precursor;
OS   Phoneutria nigriventer (Brazilian armed spider) (Ctenus nigriventer).
OC   Eukaryota; Metazoa; Ecdysozoa; Arthropoda; Chelicerata; Arachnida; Araneae;
OC   Araneomorphae; Entelegynae; Lycosoidea; Ctenidae; Phoneutria.
OX   NCBI_TaxID=6918;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [MRNA].
RC   TISSUE=Venom gland;
RX   PubMed=9839668; DOI=10.1016/s0041-0101(98)00105-6;
RA   Kalapothakis E., Penaforte C.L., Beirao P.S.L., Romano-Silva M.A.,
RA   Cruz J.S., Prado M.A.M., Guimaraes P.E.M., Gomez M.V., Prado V.F.;
RT   "Cloning of cDNAS encoding neurotoxic peptides from the spider Phoneutria
RT   nigriventer.";
RL   Toxicon 36:1843-1850(1998).
CC   -!- FUNCTION: Blocks voltage-gated sodium channels (Nav). {ECO:0000250}.
CC   -!- SUBCELLULAR LOCATION: Secreted.
CC   -!- TISSUE SPECIFICITY: Expressed by the venom gland.
CC   -!- DOMAIN: The presence of a 'disulfide through disulfide knot'
CC       structurally defines this protein as a knottin. {ECO:0000305}.
CC   -!- SIMILARITY: Belongs to the neurotoxin 03 (Tx2) family. 04 subfamily.
CC       {ECO:0000305}.
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DR   EMBL; AF014462; AAC26164.1; -; mRNA.
DR   AlphaFoldDB; O76198; -.
DR   SMR; O76198; -.
DR   ArachnoServer; AS000232; U2-ctenitoxin-Pn1b.
DR   GO; GO:0005576; C:extracellular region; IEA:UniProtKB-SubCell.
DR   GO; GO:0017080; F:sodium channel regulator activity; IEA:UniProtKB-KW.
DR   GO; GO:0090729; F:toxin activity; IEA:UniProtKB-KW.
DR   InterPro; IPR035285; CNTX.
DR   Pfam; PF17492; D_CNTX; 1.
PE   2: Evidence at transcript level;
KW   Disulfide bond; Ion channel impairing toxin; Knottin; Neurotoxin; Secreted;
KW   Signal; Toxin; Voltage-gated sodium channel impairing toxin.
FT   SIGNAL          1..17
FT                   /evidence="ECO:0000255"
FT   PROPEP          18..61
FT                   /evidence="ECO:0000250"
FT                   /id="PRO_0000035501"
FT   CHAIN           62..114
FT                   /note="U2-ctenitoxin-Pn1b"
FT                   /id="PRO_0000035502"
FT   PROPEP          115
FT                   /evidence="ECO:0000250"
FT                   /id="PRO_0000035503"
FT   DISULFID        64..78
FT                   /evidence="ECO:0000305"
FT   DISULFID        71..84
FT                   /evidence="ECO:0000305"
FT   DISULFID        75..113
FT                   /evidence="ECO:0000305"
FT   DISULFID        77..98
FT                   /evidence="ECO:0000305"
FT   DISULFID        86..96
FT                   /evidence="ECO:0000305"
SQ   SEQUENCE   115 AA;  12858 MW;  B7D3321750F7BA50 CRC64;
     MKVAVIILSI LVLAAASESI EEYREDFSRP NAMERSANDW IPTAPSAVER SADFAVEELE
     RATCAGQDKP CKETCDCCGE RGECVCALSY EGKYRCICRQ GYVWIAWYKL ASCKK