Pathways & interactions
Short name: Ergtoxin
The Ergtoxin (ErgTx) family is a class of peptides from scorpion venom that specifically block ERG (ether-a-go-go-related gene) K+ channels of the nerve, heart and endocrine cells [PMID: 11023354, PMID: 12650941, PMID: 12459475].
Peptides of the ErgTx family have from 42 to 47 amino acid residues cross-linked by four disulphide bridges. The four disulphide bridges have been assigned as C1-C4, C2-C6, C3-C7 and C5-C8 (see the schematic representation below) [PMID: 11023354]. ErgTxs consist of a triple-stranded beta-sheet and an alpha-helix, as is typical of K+ channel scorpion toxins. There is a large hydrophobic patch on the surface of the toxin, surrounding a central lysine residue located near the beta-hairpin loop between the second and third strands of the beta-sheet. It has been postulated that this hydrophobic patch is likely to form part of the binding surface of the toxin [PMID: 12650941]. Peptides of the ErgTx family possess a Knottin scaffold (see http://knottin.cbs.cnrs.fr).
Some proteins known to belong to the ErgTx family are listed below:
- ErgTx1, ErgTx2 and ErgTx3 from Centruroides elegans (Bark scorpion).
- ErgTx1, ErgTx2, ErgTx3 and ErgTx4 from Centruroides exilicauda (Bark scorpion).
- ErgTx1, ErgTx2 and ErgTx3 from Centruroides gracilis (Slenderbrown scorpion) (Florida bark scorpion).
- ErgTx1, ErgTx2, ErgTx3 and ErgTx4 from Centruroides limpidus limpidus (Mexican scorpion).
- ErgTx1, ErgTx2, ErgTx3, ErgTx4, ErgTx5 and gamma-KTx 4.12 from Centruroides sculpturatus (Bark scorpion).
- ErgTx, ErgTx2, ErgTx3, ErgTx4 and ErgTx5 from Centruroides noxius (Mexican scorpion).