PROSITE documentation PDOC60026
Ergtoxin (ErgTx) family signature


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 [1,2,3].

Peptides of the ErgTx family have from 42 to 47 amino acid residues cross-linked by four disulfide bridges. The four disulfide bridges have been assigned as C1-C4, C2-C6, C3-C7 and C5-C8 (see the schematic representation below) [1]. ErgTxs consist of a triple-stranded β-sheet and an α-helix (see <PDB:1NE5>), 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 β-hairpin loop between the second and third strands of the β-sheet. It has been postulated that this hydrophobic patch is likely to form part of the binding surface of the toxin [2]. Peptides of the ErgTx family possess a Knottin scaffold (see <PDOC60004>) [E1].

                                        #            #
                        |    |     |   |    |   |
                        |    |     +---|----|---+
                        |    +---------|----+
'C': conserved cysteine involved in a disulfide bond.
'#': positions of the cysteine, which are not involved in knottin scaffold.

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 γ-KTx 4.12 from Centruroides sculpturatus (Bark scorpion).
  • ErgTx, ErgTx2, ErgTx3, ErgTx4 and ErgTx5 from Centruroides noxius (Mexican scorpion).

We have developed a pattern that contains the eight conserved cysteines.

Expert(s) to contact by email:

Ramakumar S.

Last update:

January 2006 / First entry.


Technical section

PROSITE method (with tools and information) covered by this documentation:

ERGTX, PS60026; Ergtoxin family signature  (PATTERN)


1AuthorsScaloni A. Bottiglieri C. Ferrara L. Corona M. Gurrola G.B. Batista C. Wanke E. Possani L.D.
TitleDisulfide bridges of ergtoxin, a member of a new sub-family of peptide blockers of the ether-a-go-go-related K+ channel.
SourceFEBS. Lett. 479:156-157(2000).
PubMed ID11023354

2AuthorsTorres A.M. Bansal P. Alewood P.F. Bursill J.A. Kuchel P.W. Vandenberg J.I.
TitleSolution structure of CnErg1 (Ergtoxin), a HERG specific scorpion toxin.
SourceFEBS. Lett. 539:138-142(2003).
PubMed ID12650941

3AuthorsCorona M. Gurrola G.B. Merino E. Cassulini R.R. Valdez-Cruz N.A. Garcia B. Ramirez-Dominguez M.E. Coronas F.I.V. Zamudio F.Z. Wanke E. Possani L.D.
TitleA large number of novel Ergtoxin-like genes and ERG K+-channels blocking peptides from scorpions of the genus Centruroides.
SourceFEBS. Lett. 532:121-126(2002).
PubMed ID12459475


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