1sn4

<StructureSection load='1sn4' size='340' side='right' caption='[[1sn4]], [[Resolution|resolution]] 1.30&Aring;' scene=''>

<table><tr><td colspan='2'>[[1sn4]] is a 1 chain structure with sequence from [http://en.wikipedia.org/wiki/Mesobuthus_martensii Mesobuthus martensii]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1SN4 OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1SN4 FirstGlance]. <br>

</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=ACT:ACETATE+ION'>ACT</scene></td></tr>

<tr id='related'><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat">[[1sn1|1sn1]]</td></tr>

<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1sn4 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1sn4 OCA], [http://pdbe.org/1sn4 PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=1sn4 RCSB], [http://www.ebi.ac.uk/pdbsum/1sn4 PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=1sn4 ProSAT]</span></td></tr>

[[http://www.uniprot.org/uniprot/SCX9_MESMA SCX9_MESMA]] Binds to sodium channels (Nav) and inhibits the inactivation of the activated channels, thereby blocking neuronal transmission. This toxin is active against mammals.

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== Publication Abstract from PubMed ==

The crystal structures of two group III alpha-like toxins from the scorpion Buthus martensii Karsch, BmK M1 and BmK M4, were determined at 1.7 A and 1.3 A resolution and refined to R factors of 0.169 and 0.166, respectively. The first high-resolution structures of the alpha-like scorpion toxin show some striking features compared with structures of the "classical" alpha-toxin. Firstly, a non-proline cis peptide bond between residues 9 and 10 unusually occurs in the five-member reverse turn 8-12. Secondly, the cis peptide 9-10 mediates the spatial relationship between the turn 8-12 and the C-terminal stretch 58-64 through a pair of main-chain hydrogen bonds between residues 10 and 64 to form a unique tertiary arrangement which features the special orientation of the terminal residues 62-64. Finally, in consequence of the peculiar orientation of the C-terminal residues, the functional groups of Arg58, which are crucial for the toxin-receptor interaction, are exposed and accessible in BmK M1 and M4 rather than buried as in the classical alpha-toxins. Sequence alignment and characteristics analysis suggested that the above structural features observed in BmK M1 and M4 occur in all group III alpha-like toxins. Recently, some group III alpha-like toxins were demonstrated to occupy a receptor site different from the classical alpha-toxin. Therefore, the distinct structural features of BmK M1 and M4 presented here may provide the structural basis for the newly recognized toxin-receptor binding site selectivity. Besides, the non-proline cis peptide bonds found in these two structures play a role in the formation of the structural characteristics and in keeping accurate positions of the functionally crucial residues. This manifested a way to achieve high levels of molecular specificity and atomic precision through the strained backbone geometry.

Crystal structures of two alpha-like scorpion toxins: non-proline cis peptide bonds and implications for new binding site selectivity on the sodium channel.,He XL, Li HM, Zeng ZH, Liu XQ, Wang M, Wang DC J Mol Biol. 1999 Sep 10;292(1):125-35. PMID:10493862<ref>PMID:10493862</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 1sn4" style="background-color:#fffaf0;"></div>

== References ==

<references/>

[[Category: He, X L]]

[[Category: Li, H M]]

[[Category: Liu, X Q]]

[[Category: Wang, D C]]

[[Category: Zeng, Z H]]

[[Category: Toxin]]