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==The solution structure of remipede double-ICK toxin phi-Xibalbin3-Xt3a==
<StructureSection load='7rz3' size='340' side='right'caption='[[7rz3]]' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[7rz3]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Xibalbanus_tulumensis Xibalbanus tulumensis]. Full experimental information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=7RZ3 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=7RZ3 FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">Solution NMR, 10 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=7rz3 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=7rz3 OCA], [https://pdbe.org/7rz3 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=7rz3 RCSB], [https://www.ebi.ac.uk/pdbsum/7rz3 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=7rz3 ProSAT]</span></td></tr>
</table>
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== Publication Abstract from PubMed ==
Multivalent ligands of ion channels have proven to be both very rare and highly valuable in yielding unique insights into channel structure and pharmacology. Here, we describe a bivalent peptide from the venom of Xibalbanus tulumensis, a troglobitic arthropod from the enigmatic class Remipedia, that causes persistent calcium release by activation of ion channels involved in muscle contraction. The high-resolution solution structure of phi-Xibalbin3-Xt3a reveals a tandem repeat arrangement of inhibitor-cysteine knot (ICK) domains previously only found in spider venoms. The individual repeats of Xt3a share sequence similarity with a family of scorpion toxins that target ryanodine receptors (RyR). Single-channel electrophysiology and quantification of released Ca(2+) stores within skinned muscle fibers confirm Xt3a as a bivalent RyR modulator. Our results reveal convergent evolution of RyR targeting toxins in remipede and scorpion venoms, while the tandem-ICK repeat architecture is an evolutionary innovation that is convergent with toxins from spider venoms.

A bivalent remipede toxin promotes calcium release via ryanodine receptor activation.,Maxwell MJ, Thekkedam C, Lamboley C, Chin YK, Crawford T, Smith JJ, Liu J, Jia X, Vetter I, Laver DR, Launikonis BS, Dulhunty A, Undheim EAB, Mobli M Nat Commun. 2023 Feb 23;14(1):1036. doi: 10.1038/s41467-023-36579-w. PMID:36823422<ref>PMID:36823422</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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== References ==
<references/>
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</StructureSection>
[[Category: Large Structures]]
[[Category: Xibalbanus tulumensis]]
[[Category: Chin YK]]
[[Category: Maxwell M]]
[[Category: Mobli M]]