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1koz
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(New page: 200px<br /><applet load="1koz" size="450" color="white" frame="true" align="right" spinBox="true" caption="1koz" /> '''SOLUTION STRUCTURE OF OMEGA-GRAMMOTOXIN SIA'...)
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Revision as of 17:25, 20 November 2007
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SOLUTION STRUCTURE OF OMEGA-GRAMMOTOXIN SIA
Overview
omega-Grammotoxin SIA (GrTx) is a 36 amino acid residue protein toxin from, spider venom that inhibits P/Q and N-type voltage-gated Ca(2+) channels by, modifying voltage-dependent gating. We determined the three-dimensional, structure of GrTx using NMR spectroscopy. The toxin adopts an "inhibitor, cystine knot" motif composed of two beta-strands (Leu19-Cys21 and, Cys30-Trp32) and a beta-bulge (Trp6, Gly7-Cys30) with a +2x, -1 topology, which are connected by four chain reversals. Although GrTx was originally, identified as an inhibitor of voltage-gated Ca(2+) channel, it also binds, to K(+) channels with lower affinity. A similar cross-reaction was, observed for Hanatoxin1 (HaTx), which binds to the voltage-sensing domains, of K(+) and Ca(2+) channels with different affinities. A detailed, comparison of the GrTx and HaTx structures identifies a conserved face, containing a large hydrophobic patch surrounded by positively charged, residues. The slight differences in the surface shape, which result from, the orientation of the surface aromatic residues and/or the distribution, of the charged residues, may explain the differences in the binding, affinity of these gating modifiers with different voltage-gated ion, channels.
About this Structure
1KOZ is a Single protein structure of sequence from [1]. Full crystallographic information is available from OCA.
Reference
Solution structure of omega-grammotoxin SIA, a gating modifier of P/Q and N-type Ca(2+) channel., Takeuchi K, Park E, Lee C, Kim J, Takahashi H, Swartz K, Shimada I, J Mol Biol. 2002 Aug 16;321(3):517-26. PMID:12162963
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