View source for 1n8m


==Solution structure of Pi4, a four disulfide bridged scorpion toxin active on potassium channels==
<StructureSection load='1n8m' size='340' side='right'caption='[[1n8m]], [[NMR_Ensembles_of_Models | 10 NMR models]]' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[1n8m]] is a 1 chain structure. Full experimental information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1N8M OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1N8M FirstGlance]. <br>
</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=1n8m FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1n8m OCA], [https://pdbe.org/1n8m PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1n8m RCSB], [https://www.ebi.ac.uk/pdbsum/1n8m PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1n8m ProSAT]</span></td></tr>
</table>
== Function ==
[[https://www.uniprot.org/uniprot/KAX64_PANIM KAX64_PANIM]] Potently, completely and reversibly blocks voltage-gated potassium channel Kv1.2/KCNA2 and Shaker B (Sh). Also blocks small conductance (SK) calcium-activated potassium channel (KCNN).<ref>PMID:12919322</ref>  
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== Publication Abstract from PubMed ==
Pi4 is a short toxin found at very low abundance in the venom of Pandinus imperator scorpions. It is a potent blocker of K(+) channels. Like the other members of the alpha-KTX6 subfamily to which it belongs, it is cross-linked by four disulfide bonds. The synthetic analog (sPi4) and the natural toxin (nPi4) have been obtained by solid-phase synthesis or from scorpion venom, respectively. Analysis of two-dimensional (1)H NMR spectra of nPi4 and sPi4 indicates that both peptides have the same structure. Moreover, electrophysiological recordings of the blocking of Shaker B K(+) channels by sPi4 (K(D) = 8.5 nM) indicate that sPi4 has the same blocking activity of nPi4 (K(D) = 8.0 nM), previously described. The disulfide bonds have been independently determined by NMR and structure calculations, and by Edman-degradation/mass-spectrometry identification of peptides obtained by proteolysis of nPi4. Both approaches indicate that the pairing of the half-cystines is (6)C-(27)C, (12)C-(32)C, (16)C-(34)C, and (22)C-(37)C. The structure of the toxin has been determined by using 705 constraints derived from NMR data on sPi4. The structure, which is well defined, shows the characteristic alpha/beta scaffold of scorpion toxins. It is compared to the structure of the other alpha-KTX6 subfamily members and, in particular, to the structure of maurotoxin, which shows a different pattern of disulfide bridges despite its high degree of sequence identity (76%) with Pi4. The structure of Pi4 and the high amounts of synthetic peptide available, will enable the detailed analysis of the interaction of Pi4 with K(+) channels.

Solution structure of Pi4, a short four-disulfide-bridged scorpion toxin specific of potassium channels.,Guijarro JI, M'Barek S, Gomez-Lagunas F, Garnier D, Rochat H, Sabatier JM, Possani L, Delepierre M Protein Sci. 2003 Sep;12(9):1844-54. PMID:12930984<ref>PMID:12930984</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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<div class="pdbe-citations 1n8m" style="background-color:#fffaf0;"></div>

==See Also==
*[[Potassium channel toxin 3D structures|Potassium channel toxin 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Large Structures]]
[[Category: Barek, S M]]
[[Category: Delepierre, M]]
[[Category: Garnier, D]]
[[Category: Gomez-Lagunas, F]]
[[Category: Guijarro, J I]]
[[Category: Olamendi-Portugal, T]]
[[Category: Possani, L D]]
[[Category: Rochat, H]]
[[Category: Sabatier, J M]]
[[Category: Disulfide bridge stabilized alpha beta motif]]
[[Category: Potassium channel blocker]]
[[Category: Toxin]]