ID   TX404_LYCSI             Reviewed;         109 AA.
AC   B6DCT6;
DT   30-NOV-2010, integrated into UniProtKB/Swiss-Prot.
DT   25-NOV-2008, sequence version 1.
DT   25-MAY-2022, entry version 18.
DE   RecName: Full=U4-lycotoxin-Ls1a {ECO:0000305};
DE            Short=U4-LCTX-Ls1a {ECO:0000305};
DE   AltName: Full=Toxin-like structure LSTX-C4;
DE   Flags: Precursor;
OS   Lycosa singoriensis (Wolf spider) (Aranea singoriensis).
OC   Eukaryota; Metazoa; Ecdysozoa; Arthropoda; Chelicerata; Arachnida; Araneae;
OC   Araneomorphae; Entelegynae; Lycosoidea; Lycosidae; Lycosa.
OX   NCBI_TaxID=434756;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [LARGE SCALE MRNA].
RC   TISSUE=Venom gland;
RX   PubMed=19875276; DOI=10.1016/j.zool.2009.04.001;
RA   Zhang Y., Chen J., Tang X., Wang F., Jiang L., Xiong X., Wang M., Rong M.,
RA   Liu Z., Liang S.;
RT   "Transcriptome analysis of the venom glands of the Chinese wolf spider
RT   Lycosa singoriensis.";
RL   Zoology 113:10-18(2010).
CC   -!- FUNCTION: Enhances the high-affinity desensitization of human P2RX3
CC       purinoceptors. {ECO:0000250|UniProtKB:B3EWH0}.
CC   -!- SUBCELLULAR LOCATION: Secreted {ECO:0000250}.
CC   -!- TISSUE SPECIFICITY: Expressed by the venom gland.
CC       {ECO:0000305|PubMed:19875276}.
CC   -!- DOMAIN: The toxin is composed of 2 domains: a highly rigid N-terminal
CC       inhibitor cystine knot (knottin) domain and a rather flexible C-
CC       terminal linear cationic cytotoxin domain that forms amphiphilic alpha-
CC       helices. {ECO:0000250|UniProtKB:B3EWH0}.
CC   -!- DOMAIN: The presence of a 'disulfide through disulfide knot'
CC       structurally defines this protein as a knottin.
CC       {ECO:0000250|UniProtKB:B3EWH0}.
CC   -!- SIMILARITY: Belongs to the neurotoxin 19 (CSTX) family. 05 (U4-Lctx)
CC       subfamily. {ECO:0000305}.
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DR   EMBL; EU926020; ACI41352.1; -; mRNA.
DR   EMBL; FM864024; CAS03622.1; -; mRNA.
DR   AlphaFoldDB; B6DCT6; -.
DR   SMR; B6DCT6; -.
DR   ArachnoServer; AS000966; U4-lycotoxin-Ls1a.
DR   GO; GO:0005576; C:extracellular region; IEA:UniProtKB-SubCell.
DR   GO; GO:0090729; F:toxin activity; IEA:UniProtKB-KW.
DR   InterPro; IPR019553; Spider_toxin_CSTX_knottin.
DR   InterPro; IPR011142; Spider_toxin_CSTX_Knottin_CS.
DR   Pfam; PF10530; Toxin_35; 1.
DR   PROSITE; PS60029; SPIDER_CSTX; 1.
PE   3: Inferred from homology;
KW   Disulfide bond; Knottin; Secreted; Signal; Toxin.
FT   SIGNAL          1..22
FT                   /evidence="ECO:0000255"
FT   PROPEP          23..44
FT                   /evidence="ECO:0000250"
FT                   /id="PRO_0000401685"
FT   CHAIN           45..109
FT                   /note="U4-lycotoxin-Ls1a"
FT                   /id="PRO_0000401686"
FT   REGION          45..88
FT                   /note="Knottin domain"
FT                   /evidence="ECO:0000250|UniProtKB:B3EWH0"
FT   REGION          89..108
FT                   /note="Linear cationic cytotoxin domain"
FT                   /evidence="ECO:0000250|UniProtKB:B3EWH0"
FT   DISULFID        48..63
FT                   /evidence="ECO:0000250|UniProtKB:B3EWH0"
FT   DISULFID        55..72
FT                   /evidence="ECO:0000250|UniProtKB:B3EWH0"
FT   DISULFID        62..88
FT                   /evidence="ECO:0000250|UniProtKB:B3EWH0"
FT   DISULFID        74..86
FT                   /evidence="ECO:0000250|UniProtKB:B3EWH0"
SQ   SEQUENCE   109 AA;  12426 MW;  B5B8579C32778936 CRC64;
     MKVLVLFSVL FLTLFSYSST EAIDEFDSDA EEDMLSLMAN EQVRAKACTP RLHDCSHDRH
     SCCRGELFKD VCYCFYPEGE DKTEVCSCQQ PKSHKYIEKV VDKAKTVVG