P61095 · SFI1_SEGFL
- ProteinMu-segestritoxin-Sf1a
- StatusUniProtKB reviewed (Swiss-Prot)
- Amino acids
- Protein existenceEvidence at protein level
- Annotation score5/5
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).
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).
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).
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
Aspect | Term | |
---|---|---|
Cellular Component | extracellular region | |
Molecular Function | sodium channel regulator activity | |
Molecular Function | toxin activity |
Keywords
- Molecular function
Names & Taxonomy
Protein names
- Recommended nameMu-segestritoxin-Sf1a
- Short namesMu-SGTX-Sf1a
- Alternative names
Organism names
- Taxonomic lineageEukaryota > Metazoa > Ecdysozoa > Arthropoda > Chelicerata > Arachnida > Araneae > Araneomorphae > Haplogynae > Dysderoidea > Segestriidae > Segestria
Accessions
- Primary accessionP61095
Organism-specific databases
Subcellular Location
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.
Type | ID | Position(s) | Description | ||
---|---|---|---|---|---|
Mutagenesis | 31-33 | Complete 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 | ID | Position(s) | Description | ||
---|---|---|---|---|---|
Chain | PRO_0000087616 | 1-46 | Mu-segestritoxin-Sf1a | ||
Disulfide bond | 3↔19 | ||||
Disulfide bond | 10↔22 | ||||
Disulfide bond | 18↔42 | ||||
Disulfide bond | 24↔40 | ||||
Keywords
- PTM
Expression
Tissue specificity
Expressed by the venom gland.
Structure
Family & Domains
Features
Showing features for region.
Type | ID | Position(s) | Description | ||
---|---|---|---|---|---|
Region | 31-33 | Keys 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
- Domain
Family and domain databases
Sequence
- Sequence statusComplete
- Length46
- Mass (Da)4,982
- Last updated2004-04-26 v1
- MD5 Checksum108C69ED93C2B6BD4056A79891CDAED6
Features
Showing features for sequence conflict.
Type | ID | Position(s) | Description | ||
---|---|---|---|---|---|
Sequence conflict | 18 | in Ref. 1; AA sequence | |||
Mass Spectrometry
Keywords
- Technical term