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1y29

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==Overview==
==Overview==
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Huwentoxin-X (HWTX-X) is a novel peptide toxin, purified from the venom of, the spider Ornithoctonus huwena. It comprises 28 amino acid residues, including six cysteine residues as disulfide bridges linked in the pattern, of I-IV, II-V, and III-VI. Its cDNA, determined by rapid amplification of, 3' and 5' cDNA ends, encodes a 65-residue prepropeptide. HWTX-X shares low, sequence homology with omega-conotoxins GVIA and MVIIA, two well known, blockers of N-type Ca2+ channels. Nevertheless, whole cell studies, indicate that it can block N-type Ca2+ channels in rat dorsal root, ganglion cells (IC50 40 nm) and the blockage by HWTX-X is completely, reversible. The rank order of specificity for N-type Ca2+ channels is GVIA, approximately HWTX-X > MVIIA. In contrast to GVIA and MVIIA, HWTX-X had no, detectable effect on the twitch response of rat vas deferens to low, frequency electrical stimulation, indicating that HWTX-X has different, selectivity for isoforms of N-type Ca2+ channels, compared with GVIA or, MVIIA. A comparison of the structures of HWTX-X and GVIA reveals that they, not only adopt a common structural motif (inhibitor cystine knot), but, also have a similar functional motif, a binding surface formed by the, critical residue Tyr, and several basic residues. However, the, dissimilarities of their binding surfaces provide some insights into their, different selectivities for isoforms of N-type Ca2+ channels.
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Huwentoxin-X (HWTX-X) is a novel peptide toxin, purified from the venom of the spider Ornithoctonus huwena. It comprises 28 amino acid residues including six cysteine residues as disulfide bridges linked in the pattern of I-IV, II-V, and III-VI. Its cDNA, determined by rapid amplification of 3' and 5' cDNA ends, encodes a 65-residue prepropeptide. HWTX-X shares low sequence homology with omega-conotoxins GVIA and MVIIA, two well known blockers of N-type Ca2+ channels. Nevertheless, whole cell studies indicate that it can block N-type Ca2+ channels in rat dorsal root ganglion cells (IC50 40 nm) and the blockage by HWTX-X is completely reversible. The rank order of specificity for N-type Ca2+ channels is GVIA approximately HWTX-X > MVIIA. In contrast to GVIA and MVIIA, HWTX-X had no detectable effect on the twitch response of rat vas deferens to low frequency electrical stimulation, indicating that HWTX-X has different selectivity for isoforms of N-type Ca2+ channels, compared with GVIA or MVIIA. A comparison of the structures of HWTX-X and GVIA reveals that they not only adopt a common structural motif (inhibitor cystine knot), but also have a similar functional motif, a binding surface formed by the critical residue Tyr, and several basic residues. However, the dissimilarities of their binding surfaces provide some insights into their different selectivities for isoforms of N-type Ca2+ channels.
==About this Structure==
==About this Structure==
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[[Category: knottin]]
[[Category: knottin]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Wed Jan 23 14:05:35 2008''
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 16:01:07 2008''

Revision as of 14:01, 21 February 2008

Image:1y29.gif

1y29

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Three dimensional solution structure of huwentoxin-x by 2D 1H-NMR

Overview

Huwentoxin-X (HWTX-X) is a novel peptide toxin, purified from the venom of the spider Ornithoctonus huwena. It comprises 28 amino acid residues including six cysteine residues as disulfide bridges linked in the pattern of I-IV, II-V, and III-VI. Its cDNA, determined by rapid amplification of 3' and 5' cDNA ends, encodes a 65-residue prepropeptide. HWTX-X shares low sequence homology with omega-conotoxins GVIA and MVIIA, two well known blockers of N-type Ca2+ channels. Nevertheless, whole cell studies indicate that it can block N-type Ca2+ channels in rat dorsal root ganglion cells (IC50 40 nm) and the blockage by HWTX-X is completely reversible. The rank order of specificity for N-type Ca2+ channels is GVIA approximately HWTX-X > MVIIA. In contrast to GVIA and MVIIA, HWTX-X had no detectable effect on the twitch response of rat vas deferens to low frequency electrical stimulation, indicating that HWTX-X has different selectivity for isoforms of N-type Ca2+ channels, compared with GVIA or MVIIA. A comparison of the structures of HWTX-X and GVIA reveals that they not only adopt a common structural motif (inhibitor cystine knot), but also have a similar functional motif, a binding surface formed by the critical residue Tyr, and several basic residues. However, the dissimilarities of their binding surfaces provide some insights into their different selectivities for isoforms of N-type Ca2+ channels.

About this Structure

1Y29 is a Single protein structure of sequence from [1]. Full crystallographic information is available from OCA.

Reference

Function and solution structure of Huwentoxin-X, a specific blocker of N-type calcium channels, from the Chinese bird spider Ornithoctonus huwena., Liu Z, Dai J, Dai L, Deng M, Hu Z, Hu W, Liang S, J Biol Chem. 2006 Mar 31;281(13):8628-35. Epub 2006 Jan 26. PMID:16439354

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