Novel effects of dendrotoxin homologues on subtypes of mammalian Kv1 potassium channels expressed in Xenopus oocytes.
We have examined the effects of two DTX homologues, toxin I and toxin K, on Kv1.1, Kv1.2 and Kv1.6 channels expressed in Xenopus oocytes. Toxin I blocked all three channels; in contrast, toxin K was selective for Kv1.1. Both toxins slowed channel activation and inactivation kinetics with 10 nM toxin I approximately doubling activation and inactivation time constants of Kv1.1. For the first time, we have demonstrated the selectivity of a DTX homologue for a single cloned Kv1 channel and suggest that these toxins may sterically hinder the conformational changes that occur during channel gating.
Robertson
B
B
Department of Biochemistry, Imperial College of Science, Technology and Medicine, London, UK.
Owen
D
D
Stow
J
J
Butler
C
C
Newland
C
C
D000818:Animals; D001921:Brain / Q000187:drug effects / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D003001:Cloning, Molecular; D004546:Elapid Venoms / Q000494:pharmacology*; D004594:Electrophysiology; D006801:Humans; D015640:Ion Channel Gating; D051662:Kv1.1 Potassium Channel; D051663:Kv1.2 Potassium Channel; D009498:Neurotoxins / Q000494:pharmacology*; D009865:Oocytes; D018408:Patch-Clamp Techniques; D010455:Peptides / Q000494:pharmacology*; D026902:Potassium Channel Blockers; D015221:Potassium Channels / Q000235:genetics / Q000378:metabolism; D024642:Potassium Channels, Voltage-Gated; D051381:Rats; D014982:Xenopus laevis
D004546:Elapid Venoms; C496946:KCNA1 protein, human; C496969:KCNA2 protein, human; C496972:Kcna2 protein, rat; D051663:Kv1.2 Potassium Channel; D009498:Neurotoxins; D010455:Peptides; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; C081506:dendrotoxin K; D051662:Kv1.1 Potassium Channel; C020273:dendrotoxin