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Toxins 2014, 6(8), 2568-2579; doi:10.3390/toxins6082568

The Activation Effect of Hainantoxin-I, a Peptide Toxin from the Chinese Spider, Ornithoctonus hainana, on Intermediate-Conductance Ca2+-Activated K+ Channels

Key Laboratory of Protein Chemistry and Developmental Biology of the Ministry of Education, College of Life Sciences, Hunan Normal University, Changsha 410081, Hunan, China
These authors contributed equally to this work.
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Received: 26 May 2014 / Revised: 28 July 2014 / Accepted: 14 August 2014 / Published: 21 August 2014
(This article belongs to the Special Issue Antivenom and Venom Therapeutics)
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Abstract

Intermediate-conductance Ca2+-activated K+ (IK) channels are calcium/calmodulin-regulated voltage-independent K+ channels. Activation of IK currents is important in vessel and respiratory tissues, rendering the channels potential drug targets. A variety of small organic molecules have been synthesized and found to be potent activators of IK channels. However, the poor selectivity of these molecules limits their therapeutic value. Venom-derived peptides usually block their targets with high specificity. Therefore, we searched for novel peptide activators of IK channels by testing a series of toxins from spiders. Using electrophysiological experiments, we identified hainantoxin-I (HNTX-I) as an IK-channel activator. HNTX-I has little effect on voltage-gated Na+ and Ca2+ channels from rat dorsal root ganglion neurons and on the heterologous expression of voltage-gated rapidly activating delayed rectifier K+ channels (human ether-à-go-go-related gene; human ERG) in HEK293T cells. Only 35.2% ± 0.4% of the currents were activated in SK channels, and there was no effect on BK channels. We demonstrated that HNTX-I was not a phrenic nerve conduction blocker or acutely toxic. This is believed to be the first report of a peptide activator effect on IK channels. Our study suggests that the activity and selectivity of HNTX-I on IK channels make HNTX-I a promising template for designing new drugs for cardiovascular diseases. View Full-Text
Keywords: IK channels; peptide activator; HNTX-I; selectivity; new drug design IK channels; peptide activator; HNTX-I; selectivity; new drug design
This is an open access article distributed under the Creative Commons Attribution License (CC BY 3.0).

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MDPI and ACS Style

Huang, P.; Zhang, Y.; Chen, X.; Zhu, L.; Yin, D.; Zeng, X.; Liang, S. The Activation Effect of Hainantoxin-I, a Peptide Toxin from the Chinese Spider, Ornithoctonus hainana, on Intermediate-Conductance Ca2+-Activated K+ Channels. Toxins 2014, 6, 2568-2579.

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