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1q2j

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{{STRUCTURE_1q2j| PDB=1q2j | SCENE= }}
{{STRUCTURE_1q2j| PDB=1q2j | SCENE= }}
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'''Structural basis for tetrodotoxin-resistant sodium channel binding by mu-conotoxin SmIIIA'''
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===Structural basis for tetrodotoxin-resistant sodium channel binding by mu-conotoxin SmIIIA===
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==Overview==
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SmIIIA is a new micro-conotoxin isolated recently from Conus stercusmuscarum. Although it shares several biochemical characteristics with other micro-conotoxins (the arrangement of cysteine residues and a conserved arginine believed to interact with residues near the channel pore), it has several distinctive features, including the absence of hydroxyproline, and is the first specific antagonist of tetrodotoxin-resistant voltage-gated sodium channels to be characterized. It therefore represents a potentially useful tool to investigate the functional roles of these channels. We have determined the three-dimensional structure of SmIIIA in aqueous solution. Consistent with the absence of hydroxyprolines, SmIIIA adopts a single conformation with all peptide bonds in the trans configuration. The spatial orientations of several conserved Arg and Lys side chains, including Arg14 (using a consensus numbering system), which plays a key role in sodium channel binding, are similar to those in other micro-conotoxins but the N-terminal regions differ, reflecting the trans conformation for the peptide bond preceding residue 8 in SmIIIA, as opposed to the cis conformation in micro-conotoxins GIIIA and GIIIB. Comparison of the surfaces of SmIIIA with other micro-conotoxins suggests that the affinity of SmIIIA for TTX-resistant channels is influenced by the Trp15 side chain, which is unique to SmIIIA. Arg17, which replaces Lys in the other micro-conotoxins, may also be important. Consistent with these inferences from the structure, assays of two chimeras of SmIIIA and PIIIA in which their N- and C-terminal halves were recombined, indicated that residues in the C-terminal half of SmIIIA confer affinity for tetrodotoxin-resistant sodium channels in the cell bodies of frog sympathetic neurons. SmIIIA and the chimera possessing the C-terminal half of SmIIIA also inhibit tetrodotoxin-resistant sodium channels in the postganglionic axons of sympathetic neurons, as indicated by their inhibition of C-neuron compound action potentials that persist in the presence of tetrodotoxin.
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{{ABSTRACT_PUBMED_12970353}}
==About this Structure==
==About this Structure==
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Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1Q2J OCA].
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Full experimental information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1Q2J OCA].
==Reference==
==Reference==
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[[Category: Yoshikami, D.]]
[[Category: Yoshikami, D.]]
[[Category: Mu-conotoxin]]
[[Category: Mu-conotoxin]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 05:47:04 2008''
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 29 08:28:32 2008''

Revision as of 05:28, 29 July 2008

Image:1q2j.png

Template:STRUCTURE 1q2j

Structural basis for tetrodotoxin-resistant sodium channel binding by mu-conotoxin SmIIIA

Template:ABSTRACT PUBMED 12970353

About this Structure

Full experimental information is available from OCA.

Reference

Structural basis for tetrodotoxin-resistant sodium channel binding by mu-conotoxin SmIIIA., Keizer DW, West PJ, Lee EF, Yoshikami D, Olivera BM, Bulaj G, Norton RS, J Biol Chem. 2003 Nov 21;278(47):46805-13. Epub 2003 Sep 10. PMID:12970353

Page seeded by OCA on Tue Jul 29 08:28:32 2008

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