1WMT

Scorpion toxin (IsTX) from Opisthacanthus madagascariensis


Experimental Data Snapshot

  • Method: SOLUTION NMR
  • Conformers Calculated: 100 
  • Conformers Submitted: 20 
  • Selection Criteria: structures with the lowest energy 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Solution structure of IsTX: A male scorpion toxin from Opisthacanthus madagascariensis (Ischnuridae)

Yamaji, N.Dai, L.Sugase, K.Andriantsiferana, M.Nakajima, T.Iwashita, T.

(2004) Eur.J.Biochem. 271: 3855-3864

  • DOI: 10.1111/j.1432-1033.2004.04322.x

  • PubMed Abstract: 
  • The novel sex-specific potassium channel inhibitor IsTX, a 41-residue peptide, was isolated from the venom of male Opisthacanthus madagascariensis. Two-dimensional NMR techniques revealed that the structure of IsTX contains a cysteine-stabilized alph ...

    The novel sex-specific potassium channel inhibitor IsTX, a 41-residue peptide, was isolated from the venom of male Opisthacanthus madagascariensis. Two-dimensional NMR techniques revealed that the structure of IsTX contains a cysteine-stabilized alpha/beta-fold. IsTX is classified, based on its sequential and structural similarity, in the scorpion short toxin family alpha-KTx6. The alpha-KTx6 family contains a single alpha-helix and two beta-strands connected by four disulfide bridges and binds to voltage-gated K(+) channels and apamin-sensitive Ca(2+)-activated K(+) channels. The three-dimensional structure of IsTX is similar to that of Heterometrus spinifer toxin (HsTX1). HsTX1 blocks the Kv1.3 channel at picomolar concentrations, whereas IsTX has much lower affinities (10 000-fold). To investigate the structure-activity relationship, the geometry of sidechains and electrostatic surface potential maps were compared with HsTX1. As a result of the comparison of the primary structures, Lys27 of IsTX was conserved at the same position in HsTX1. The analogous Lys23 of HsTX1, the most critical residue for binding to potassium channels, binds to the channel pore. However, IsTX has fewer basic residues to interact with acidic channel surfaces than HsTX1. MALDI-TOF MS analysis clearly indicated that IsTX was found in male scorpion venom, but not in female. This is the first report that scorpion venom contains sex-specific compounds.


    Organizational Affiliation

    Suntory Institute for Bioorganic Research, Mishima-Gun, Osaka 618-8503, Japan. yamaji@sunbor.or.jp




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
IsTX
A
41Opisthacanthus madagascariensisMutation(s): 0 
Find proteins for P0C194 (Opisthacanthus madagascariensis)
Go to UniProtKB:  P0C194
Experimental Data & Validation

Experimental Data

  • Method: SOLUTION NMR
  • Conformers Calculated: 100 
  • Conformers Submitted: 20 
  • Selection Criteria: structures with the lowest energy 

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2004-10-19
    Type: Initial release
  • Version 1.1: 2008-04-30
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance