ID   TX2_LOXIN               Reviewed;         105 AA.
AC   Q6B4T4;
DT   28-NOV-2006, integrated into UniProtKB/Swiss-Prot.
DT   13-SEP-2004, sequence version 1.
DT   25-MAY-2022, entry version 41.
DE   RecName: Full=U1-sicaritoxin-Li1b;
DE            Short=U1-SCRTX-Li1b;
DE   AltName: Full=LiTx2 {ECO:0000303|PubMed:15302533};
DE   Flags: Precursor;
OS   Loxosceles intermedia (Brown spider).
OC   Eukaryota; Metazoa; Ecdysozoa; Arthropoda; Chelicerata; Arachnida; Araneae;
OC   Araneomorphae; Haplogynae; Scytodoidea; Sicariidae; Loxosceles.
OX   NCBI_TaxID=58218;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [MRNA], PROTEIN SEQUENCE OF 37-53, AND SUBCELLULAR
RP   LOCATION.
RC   TISSUE=Venom, and Venom gland;
RX   PubMed=15302533; DOI=10.1016/j.toxicon.2004.05.028;
RA   de Castro C.S., Silvestre F.G., Araujo S.C., Yazbeck G.M., Mangili O.C.,
RA   Cruz I., Chavez-Olortegui C., Kalapothakis E.;
RT   "Identification and molecular cloning of insecticidal toxins from the venom
RT   of the brown spider Loxosceles intermedia.";
RL   Toxicon 44:273-280(2004).
CC   -!- FUNCTION: Toxin active against insects (S.frugiperda larvae). May act
CC       on sodium (Nav) or calcium (Cav) channels.
CC   -!- SUBCELLULAR LOCATION: Secreted {ECO:0000269|PubMed:15302533}.
CC   -!- TISSUE SPECIFICITY: Expressed by the venom gland.
CC       {ECO:0000305|PubMed:15302533}.
CC   -!- DOMAIN: The presence of a 'disulfide through disulfide knot'
CC       structurally defines this protein as a knottin. {ECO:0000250}.
CC   -!- SIMILARITY: Belongs to the neurotoxin 28 (Litx) family. {ECO:0000305}.
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DR   EMBL; AY681976; AAT85611.1; -; mRNA.
DR   AlphaFoldDB; Q6B4T4; -.
DR   SMR; Q6B4T4; -.
DR   ArachnoServer; AS000251; U1-sicaritoxin-Li1b.
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.
PE   1: Evidence at protein level;
KW   Amidation; Cleavage on pair of basic residues; Direct protein sequencing;
KW   Disulfide bond; Ion channel impairing toxin; Knottin; Neurotoxin; Secreted;
KW   Signal; Toxin.
FT   SIGNAL          1..19
FT                   /evidence="ECO:0000255"
FT   PROPEP          20..36
FT                   /evidence="ECO:0000269|PubMed:15302533"
FT                   /id="PRO_0000262658"
FT   CHAIN           37..82
FT                   /note="U1-sicaritoxin-Li1b"
FT                   /id="PRO_0000262659"
FT   PROPEP          86..105
FT                   /id="PRO_0000262660"
FT   MOD_RES         82
FT                   /note="Arginine amide"
FT                   /evidence="ECO:0000255"
FT   DISULFID        38..55
FT                   /evidence="ECO:0000250"
FT   DISULFID        46..60
FT                   /evidence="ECO:0000250"
FT   DISULFID        54..73
FT                   /evidence="ECO:0000250"
FT   DISULFID        62..71
FT                   /evidence="ECO:0000250"
FT   CONFLICT        38
FT                   /note="C -> G (in Ref. 1; AA sequence)"
FT                   /evidence="ECO:0000305"
FT   CONFLICT        53
FT                   /note="W -> D (in Ref. 1; AA sequence)"
FT                   /evidence="ECO:0000305"
SQ   SEQUENCE   105 AA;  12054 MW;  0FB8D28E1CC30174 CRC64;
     MKLLFEGLLV LVLIAFVVAE FESDAEKWEA LITQERACKG EGVKGCYYEA DDWCCKKTPC
     KCPAWSHERE CRCTQPCNPS CRGKRALMVD PETHRMLSLH RLSEE