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| | {{STRUCTURE_1wmt| PDB=1wmt | SCENE= }} | | {{STRUCTURE_1wmt| PDB=1wmt | SCENE= }} |
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| - | '''Scorpion toxin (IsTX) from Opisthacanthus madagascariensis'''
| + | ===Scorpion toxin (IsTX) from Opisthacanthus madagascariensis=== |
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| - | ==Overview==
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| - | 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. | + | The line below this paragraph, {{ABSTRACT_PUBMED_15373831}}, adds the Publication Abstract to the page |
| | + | (as it appears on PubMed at http://www.pubmed.gov), where 15373831 is the PubMed ID number. |
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| | + | {{ABSTRACT_PUBMED_15373831}} |
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| | ==About this Structure== | | ==About this Structure== |
| - | Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1WMT OCA]. | + | Full experimental information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1WMT OCA]. |
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| | ==Reference== | | ==Reference== |
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| | [[Category: Potassium channel blocker]] | | [[Category: Potassium channel blocker]] |
| | [[Category: Scorpion toxin]] | | [[Category: Scorpion toxin]] |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 13:53:16 2008'' | + | |
| | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jul 28 08:43:47 2008'' |
Revision as of 05:43, 28 July 2008
Template:STRUCTURE 1wmt
Scorpion toxin (IsTX) from Opisthacanthus madagascariensis
Template:ABSTRACT PUBMED 15373831
About this Structure
Full experimental information is available from OCA.
Reference
Solution structure of IsTX. A male scorpion toxin from Opisthacanthus madagascariensis (Ischnuridae)., Yamaji N, Dai L, Sugase K, Andriantsiferana M, Nakajima T, Iwashita T, Eur J Biochem. 2004 Oct;271(19):3855-64. PMID:15373831
Page seeded by OCA on Mon Jul 28 08:43:47 2008
