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==PANDINUS TOXIN K-A (PITX-KA) FROM PANDINUS IMPERATOR, NMR, 20 STRUCTURES==
<StructureSection load='2pta' size='340' side='right'caption='[[2pta]]' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[2pta]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Pandinus_imperator Pandinus imperator]. Full experimental information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2PTA OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=2PTA FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">Solution NMR, 20 models</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=2pta FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2pta OCA], [https://pdbe.org/2pta PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=2pta RCSB], [https://www.ebi.ac.uk/pdbsum/2pta PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=2pta ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/KAX71_PANIM KAX71_PANIM] Potent inhibitor of the A-type voltage-gated potassium channels. Most potent inhibitor of Kv1.2/KCNA2 channels. Reversibly block the Shaker B potassium-channels (Kv1.1 sub-family).<ref>PMID:8660410</ref> 
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== Publication Abstract from PubMed ==
PiTX-K alpha, a 35-residue peptide recently isolated from the venom of Pandinus imperator, blocks the rapidly inactivating (A-type) K+ channel(s) in rat brain synaptosomes and the cloned Kv 1.2 potassium channel at very low toxin concentrations (6 nM and 32 pM, respectively) [Rogowski, R. S., Collins, J. H., O'Neil, T. J., Gustafson, T. A., Werkman, T. A., Rogawski, M. A., Tenenholz, T. C., Weber, D. J., &amp; Blaustein, M. P. (1996) Mol. Pharmacol. 50, 1167-1177]. The three-dimensional structure of PiTX-K alpha was determined using NMR spectroscopy in order to understand its selectivity and affinity toward K+ channels. PiTX-K alpha was found to have an alpha-helix from residues 10 to 21 and two beta-strands (betaI, 26-28; betaII, 33-35) connected by a type II beta-turn to form a small antiparallel beta-sheet. Three disulfide bonds, which are conserved in all members of the charybdotoxin family (alpha-K toxins), anchor one face of the alpha-helix to the beta-sheet. The N-terminal portion of PiTX-K alpha has three fewer residues than other alpha-K toxins such as charybdotoxin. Rather than forming a third beta-strand as found for other alpha-K toxins, the N-terminal region of PiTX-K alpha adopts an extended conformation. This structural difference in PiTX-K alpha together with differences in sequence at Pro-10, Tyr-14, and Asn-25 (versus Ser-10, Trp-14, and Arg-25 in CTX) may explain why PiTX-K alpha does not block maxi-K+ channels. Differences in three-dimensional structure between PiTX-K alpha and charybdotoxin are also observed in both the tight turn and the loop that connects the first beta-strand to the alpha-helix. As a result, side chains of two residues (Tyr-23 and Arg-31) are in regions of PiTX-K alpha that probably interact with rapidly inactivating A-type K+ channels. The analogous residues in charybdotoxin are positioned differently on the toxin surface. Thus, the locations of Tyr-23 and Arg-31 side chains in PiTX-K alpha could explain why this toxin blocks A-type channels at much lower concentrations than does charybdotoxin.

Solution structure for Pandinus toxin K-alpha (PiTX-K alpha), a selective blocker of A-type potassium channels.,Tenenholz TC, Rogowski RS, Collins JH, Blaustein MP, Weber DJ Biochemistry. 1997 Mar 11;36(10):2763-71. PMID:9062103<ref>PMID:9062103</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 2pta" 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: Pandinus imperator]]
[[Category: Blaustein MP]]
[[Category: Collins JH]]
[[Category: Rogowski RS]]
[[Category: Tenenholz TC]]
[[Category: Weber DJ]]