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New page: left|200px<br /><applet load="1ktx" size="450" color="white" frame="true" align="right" spinBox="true" caption="1ktx" /> '''KALIOTOXIN (1-37) SHOWS STRUCTURAL DIFFERENC...
 
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[[Image:1ktx.jpg|left|200px]]<br /><applet load="1ktx" size="450" color="white" frame="true" align="right" spinBox="true"
caption="1ktx" />
'''KALIOTOXIN (1-37) SHOWS STRUCTURAL DIFFERENCES WITH RELATED POTASSIUM CHANNEL BLOCKERS'''<br />


==Overview==
==KALIOTOXIN (1-37) SHOWS STRUCTURAL DIFFERENCES WITH RELATED POTASSIUM CHANNEL BLOCKERS==
The three-dimensional structure of kaliotoxin (1-37), KTX(1-37), a toxin, from the scorpion Androctonus mauretanicus mauretanicus that blocks, calcium-dependent potassium channels, has been determined by NMR. This, toxin is homologous with other scorpion toxins such as charybdotoxin, (ChTX) or iberiotoxin (IbTX) for which the structures are already known, but the presence of prolines in the expected alpha-helical region, suggested that there may be some major difference in the structure of KTX, that could be related to its different selectivity. Proline residues are, also found in the homologous region of other scorpion toxins such as, noxiustoxin or margatoxin. Our results indicate that KTX(1-37) contains, the same sequence of secondary structure elements as ChTX but that the, helical region is shorter and distorted due to the presence of two, prolines. The distortion consists of a bending in the alpha-helix and in, the presence of a 3(10) helix turn in the last three residues., Furthermore, the increased length of the extended structure preceding the, helix favors a different packing of this part of the molecule with respect, to the secondary structure elements. This change in folding modifies the, accessibility of the conserved 27Lys which is known, from mutation, studies, to be involved in channel blocking by ChTX.
<StructureSection load='1ktx' size='340' side='right'caption='[[1ktx]]' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[1ktx]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Androctonus_mauritanicus_mauritanicus Androctonus mauritanicus mauritanicus]. Full experimental information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1KTX OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1KTX FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">Solution NMR</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=NH2:AMINO+GROUP'>NH2</scene></td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=1ktx FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1ktx OCA], [https://pdbe.org/1ktx PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1ktx RCSB], [https://www.ebi.ac.uk/pdbsum/1ktx PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1ktx ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/KAX31_ANDMA KAX31_ANDMA] Potent inhibitor of large conductance calcium-activated potassium channels (BK-Ca). Also binds to the dendrotoxin sensitive voltage-dependent potassium channel. It appears to block channel activity by a simple bimolecular inhibition process. Induces a transient period of fast flickering in the channel openings, followed by an almost complete blockade of the channel. Its binding affinity to rat brain synaptosomes is 5-fold higher than this of KTX-3. Binding of the toxin to the channel is associated with significant structural rearrangements in both molecules.
== Evolutionary Conservation ==
[[Image:Consurf_key_small.gif|200px|right]]
Check<jmol>
  <jmolCheckbox>
    <scriptWhenChecked>; select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/kt/1ktx_consurf.spt"</scriptWhenChecked>
    <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.spt</scriptWhenUnchecked>
    <text>to colour the structure by Evolutionary Conservation</text>
  </jmolCheckbox>
</jmol>, as determined by [http://consurfdb.tau.ac.il/ ConSurfDB]. You may read the [[Conservation%2C_Evolutionary|explanation]] of the method and the full data available from [http://bental.tau.ac.il/new_ConSurfDB/main_output.php?pdb_ID=1ktx ConSurf].
<div style="clear:both"></div>


==About this Structure==
==See Also==
1KTX is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Androctonus_mauretanicus_mauretanicus Androctonus mauretanicus mauretanicus] with NH2 as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1KTX OCA].
*[[Potassium channel toxin 3D structures|Potassium channel toxin 3D structures]]
 
__TOC__
==Reference==
</StructureSection>
Kaliotoxin (1-37) shows structural differences with related potassium channel blockers., Fernandez I, Romi R, Szendeffy S, Martin-Eauclaire MF, Rochat H, Van Rietschoten J, Pons M, Giralt E, Biochemistry. 1994 Nov 29;33(47):14256-63. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=7524673 7524673]
[[Category: Androctonus mauritanicus mauritanicus]]
[[Category: Androctonus mauretanicus mauretanicus]]
[[Category: Large Structures]]
[[Category: Single protein]]
[[Category: Fernandez I]]
[[Category: Fernandez, I.]]
[[Category: Giralt E]]
[[Category: Giralt, E.]]
[[Category: Martin-Eauclaire M-F]]
[[Category: Martin-Eauclaire, M.F.]]
[[Category: Pons M]]
[[Category: Pons, M.]]
[[Category: Rochat H]]
[[Category: Rietschtoten, J.Van.]]
[[Category: Romi R]]
[[Category: Rochat, H.]]
[[Category: Szendefi S]]
[[Category: Romi, R.]]
[[Category: Van Rietschtoten J]]
[[Category: Szendefi, S.]]
[[Category: NH2]]
[[Category: neurotoxin(potassium channel inhibitor)]]
 
''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Tue Nov 20 19:52:38 2007''

Latest revision as of 08:03, 3 April 2024

KALIOTOXIN (1-37) SHOWS STRUCTURAL DIFFERENCES WITH RELATED POTASSIUM CHANNEL BLOCKERS

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