ID   SFI2_SEGFL              Reviewed;          46 AA.
AC   P61096;
DT   26-APR-2004, integrated into UniProtKB/Swiss-Prot.
DT   26-APR-2004, sequence version 1.
DT   25-MAY-2022, entry version 45.
DE   RecName: Full=Mu-segestritoxin-Sf1b {ECO:0000305};
DE            Short=Mu-SGTX-Sf1b {ECO:0000305};
DE   AltName: Full=F5.7 {ECO:0000303|PubMed:11689233};
DE   AltName: Full=Toxin SFI2 {ECO:0000303|PubMed:11689233};
OS   Segestria florentina (Tube-web spider) (Segestria gracilis).
OC   Eukaryota; Metazoa; Ecdysozoa; Arthropoda; Chelicerata; Arachnida; Araneae;
OC   Araneomorphae; Haplogynae; Dysderoidea; Segestriidae; Segestria.
OX   NCBI_TaxID=31925;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [MRNA], PROTEIN SEQUENCE OF 1-18, FUNCTION, SUBCELLULAR
RP   LOCATION, MASS SPECTROMETRY, AND TOXIC DOSE.
RC   TISSUE=Venom, and Venom gland;
RX   PubMed=11689233; DOI=10.1016/s0041-0101(01)00181-7;
RA   Lipkin A., Kozlov S., Nosyreva E., Blake A., Windass J.D., Grishin E.;
RT   "Novel insecticidal toxins from the venom of the spider Segestria
RT   florentina.";
RL   Toxicon 40:125-130(2002).
CC   -!- FUNCTION: Insecticidal toxin. Causes flaccid paralysis followed by
CC       death when injected into Heliothis virescens larvae. Does not induce
CC       any toxic effects when injected intravenously into adult mice at a dose
CC       of 1.25 mg/kg body weight. {ECO:0000269|PubMed:11689233}.
CC   -!- SUBCELLULAR LOCATION: Secreted {ECO:0000269|PubMed:11689233}.
CC   -!- TISSUE SPECIFICITY: Expressed by the venom gland.
CC       {ECO:0000305|PubMed:11689233}.
CC   -!- DOMAIN: The presence of a 'disulfide through disulfide knot'
CC       structurally defines this protein as a knottin.
CC       {ECO:0000250|UniProtKB:P61095}.
CC   -!- MASS SPECTROMETRY: Mass=4993; Method=MALDI;
CC       Evidence={ECO:0000269|PubMed:11689233};
CC   -!- TOXIC DOSE: LD(50) is 7 mg/kg on H.virescens larvae.
CC       {ECO:0000269|PubMed:11689233}.
CC   -!- SIMILARITY: Belongs to the neurotoxin 16 (SFI) family. {ECO:0000305}.
CC   -!- CAUTION: Mass spectrometry experiment was done on the entire protein
CC       whose known sequence is incomplete (sequence of 1-18). The difference
CC       between measured (4993) and calculated (5136) mass resides in the fact
CC       that the sequence of this entire protein is maybe not identical to the
CC       sequence shown. {ECO:0000305}.
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DR   AlphaFoldDB; P61096; -.
DR   SMR; P61096; -.
DR   ArachnoServer; AS000117; mu-segestritoxin-Sf1b.
DR   GO; GO:0005576; C:extracellular region; IEA:UniProtKB-SubCell.
DR   GO; GO:0090729; F:toxin activity; IEA:UniProtKB-KW.
DR   InterPro; IPR012633; Toxin_28.
DR   Pfam; PF08115; Toxin_28; 1.
PE   1: Evidence at protein level;
KW   Direct protein sequencing; Disulfide bond; Knottin; Secreted; Toxin.
FT   CHAIN           1..46
FT                   /note="Mu-segestritoxin-Sf1b"
FT                   /evidence="ECO:0000305|PubMed:11689233"
FT                   /id="PRO_0000087617"
FT   REGION          31..33
FT                   /note="Keys region for toxin activity"
FT                   /evidence="ECO:0000250|UniProtKB:P61095"
FT   DISULFID        3..19
FT                   /evidence="ECO:0000250|UniProtKB:P61095"
FT   DISULFID        10..22
FT                   /evidence="ECO:0000250|UniProtKB:P61095"
FT   DISULFID        18..42
FT                   /evidence="ECO:0000250|UniProtKB:P61095"
FT   DISULFID        24..40
FT                   /evidence="ECO:0000250|UniProtKB:P61095"
SQ   SEQUENCE   46 AA;  5136 MW;  CBFCD66F6292D8F6 CRC64;
     KECMADETVC YIHNHNNCCG SCLCLNGPYA RPWEMLVGNC KCGPKE