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P61095 · SFI1_SEGFL

Function

function

Insecticidal toxin (PubMed:11689233).
It inhibits insect voltage-gated sodium channels (Nav) by partially blocking the channel pore (1 uM inhibits 55.7% sodium current in DUM neurons from the American cockroach), not by acting as a gating modifier (PubMed:25559770).
The inhibition is only partially reversible (about 25% recovery) after prolonged washout (PubMed:25559770).
In vivo, the toxin causes flaccid paralysis followed by death when injected into Heliothis virescens larvae (PubMed:11689233).
It also causes uncoordinated movements followed by full paralysis to sheep blowflies (Lucilia cuprina) (PubMed:25559770).

Miscellaneous

Negative results: does not show significant effects on voltage-gated calcium channel (Cav) and voltage-gated potassium channel (Kv) currents in cockroach DUM neurons (PubMed:25559770).
In vivo, does not induce any toxic effects when injected intravenously into adult mice at a dose of 1.5 mg/kg body weight (PubMed:25559770).
Exists in two forms, due to cis-trans isomerization at 31-Arg-Pro-32.

Biotechnology

Could be considered as a biological insecticide candidate, when fused to Galanthus nivalis agglutinin (GNA), a protein with the potential to cross the insect gut (PubMed:15037094, PubMed:16206236).
This chimeric Sf1a/GNA variant shows a gain in toxicity against insects when administered orally, while maintaining similar effects as the wild-type toxin when injected (PubMed:15037094).
This variant has been found to be orally toxic against larvae of the tomato moth (Laconobia oleracea), the rice brown planthopper (Nilaparvata lugens), and the peach-potato aphid (Myzus persicae) (PubMed:15037094, PubMed:16206236).

GO annotations

AspectTerm
Cellular Componentextracellular region
Molecular Functionsodium channel regulator activity
Molecular Functiontoxin activity

Keywords

Names & Taxonomy

Protein names

  • Recommended name
    Mu-segestritoxin-Sf1a
  • Short names
    Mu-SGTX-Sf1a
  • Alternative names
    • F5.6
    • Toxin SFI1

Organism names

Accessions

  • Primary accession
    P61095

Organism-specific databases

Subcellular Location

Keywords

Phenotypes & Variants

Toxic dose

LD50 is 10 mg/kg on H.virescens larvae.
PD50 are 2.2 +-0.2 and 1.5 +-0.3 nmol/g (native and recombinant toxins, respectively) when injected into sheep blowfiles (L.cuprina).

Features

Showing features for mutagenesis.

TypeIDPosition(s)Description
Mutagenesis31-33Complete loss of insecticidal activity as well as complete loss of inhibition of sodium current in DUM neurons.

PTM/Processing

Features

Showing features for chain, disulfide bond.

Type
IDPosition(s)Description
ChainPRO_00000876161-46Mu-segestritoxin-Sf1a
Disulfide bond3↔19
Disulfide bond10↔22
Disulfide bond18↔42
Disulfide bond24↔40

Keywords

Expression

Tissue specificity

Expressed by the venom gland.

Family & Domains

Features

Showing features for region.

TypeIDPosition(s)Description
Region31-33Keys region for toxin activity

Domain

The presence of a 'disulfide through disulfide knot' structurally defines this protein as a knottin.

Sequence similarities

Belongs to the neurotoxin 16 (SFI) family.

Keywords

Family and domain databases

Sequence

  • Sequence status
    Complete
  • Length
    46
  • Mass (Da)
    4,982
  • Last updated
    2004-04-26 v1
  • MD5 Checksum
    108C69ED93C2B6BD4056A79891CDAED6
KECMTDGTVCYIHNHNDCCGSCLCSNGPIARPWEMMVGNCMCGPKA

Features

Showing features for sequence conflict.

TypeIDPosition(s)Description
Sequence conflict18in Ref. 1; AA sequence

Mass Spectrometry

Molecular mass is 4,973 Da. Determined by MALDI.

Keywords

Similar Proteins

Disclaimer

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