ID   TX21B_PHONI             Reviewed;          80 AA.
AC   P81793;
DT   23-JAN-2002, integrated into UniProtKB/Swiss-Prot.
DT   01-MAY-1999, sequence version 1.
DT   25-MAY-2022, entry version 58.
DE   RecName: Full=U6-ctenitoxin-Pn1a {ECO:0000305};
DE            Short=U6-CNTX-Pn1a {ECO:0000305};
DE   AltName: Full=Neurotoxin Pn3A {ECO:0000303|PubMed:9839681};
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=9839681; DOI=10.1016/s0041-0101(98)00127-5;
RA   Kalapothakis E., Penaforte C.L., Leao R.M., Cruz J.S., Prado V.F.,
RA   Cordeiro M.N., Diniz C.R., Romano-Silva M.A., Prado M.A.M., Gomez M.V.,
RA   Beirao P.S.L.;
RT   "Cloning, cDNA sequence analysis and patch clamp studies of a toxin from
RT   the venom of the armed spider (Phoneutria nigriventer).";
RL   Toxicon 36:1971-1980(1998).
CC   -!- FUNCTION: Antagonist of L-type calcium channels (Cav1/CACNA1).
CC       {ECO:0000250}.
CC   -!- SUBCELLULAR LOCATION: Secreted {ECO:0000305|PubMed:9839681}.
CC   -!- TISSUE SPECIFICITY: Expressed by the venom gland.
CC       {ECO:0000305|PubMed:9839681}.
CC   -!- DOMAIN: The presence of a 'disulfide through disulfide knot'
CC       structurally defines this protein as a knottin.
CC       {ECO:0000250|UniProtKB:P30288}.
CC   -!- SIMILARITY: Belongs to the neurotoxin 02 (plectoxin) family. 01 (Tx3)
CC       subfamily. {ECO:0000305}.
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DR   AlphaFoldDB; P81793; -.
DR   ArachnoServer; AS000271; U6-ctenitoxin-Pn1a.
DR   GO; GO:0005576; C:extracellular region; IEA:UniProtKB-SubCell.
DR   GO; GO:0005246; F:calcium channel regulator activity; IEA:UniProtKB-KW.
DR   GO; GO:0008200; F:ion channel inhibitor activity; IEA:InterPro.
DR   GO; GO:0090729; F:toxin activity; IEA:UniProtKB-KW.
DR   CDD; cd12960; Spider_toxin; 1.
DR   InterPro; IPR004169; Spidertoxin.
DR   Pfam; PF02819; Toxin_9; 1.
PE   3: Inferred from homology;
KW   Calcium channel impairing toxin; Disulfide bond;
KW   Ion channel impairing toxin; Knottin; Neurotoxin; Secreted; Signal; Toxin;
KW   Voltage-gated calcium channel impairing toxin.
FT   SIGNAL          1..21
FT                   /evidence="ECO:0000255"
FT   PROPEP          22..37
FT                   /evidence="ECO:0000250"
FT                   /id="PRO_0000035514"
FT   CHAIN           38..71
FT                   /note="U6-ctenitoxin-Pn1a"
FT                   /id="PRO_0000035515"
FT   PROPEP          72..80
FT                   /evidence="ECO:0000250"
FT                   /id="PRO_0000035516"
FT   DISULFID        39..54
FT                   /evidence="ECO:0000250|UniProtKB:P30288"
FT   DISULFID        46..59
FT                   /evidence="ECO:0000250|UniProtKB:P30288"
FT   DISULFID        53..69
FT                   /evidence="ECO:0000250|UniProtKB:P30288"
FT   DISULFID        61..67
FT                   /evidence="ECO:0000250|UniProtKB:P30288"
SQ   SEQUENCE   80 AA;  8938 MW;  B5BF209257EB6793 CRC64;
     MWLKIQVFVL ALALITLGIQ AEPNSGPNNP LIQEEARACA DVYKECWYPE KPCCKDRACQ
     CTLGMTCKCK ATLGDLFGRR