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PMID: 7506068 Published · ppublish English Journal Article Research Support, U.S. Gov't, P.H.S.

Mechanism of charybdotoxin block of a voltage-gated K+ channel.

Biophysical journal ·Vol. 65 ·No. 4 ·1993-10-00 ·Pages 1613-9

Goldstein SA, Miller C

Abstract

Charybdotoxin block of a Shaker K+ channel was studied in Xenopus oocyte macropatches. Toxin on rate increases linearly with toxin concentration in an ionic strength-dependent fashion and is competitively diminished by tetraethylammonium. On rate is insensitive to transmembrane voltage and to K+ on the opposite side of the membrane. Conversely, toxin off rate is insensitive to toxin concentration, ionic strength, and added tetraethylammonium but is enhanced by membrane depolarization or K+ (or Na+) in the trans solution. Charge neutralization of charybdotoxin Lys27, however, renders off rate voltage insensitive. Our results argue that block of voltage-gated K+ channels results from the binding of one toxin molecule, so that Lys27 enters the pore and interacts with K+ (or Na+) in the ion conduction pathway.

MeSH Terms

Animals Binding, Competitive Biophysical Phenomena Biophysics Charybdotoxin Drosophila Female Ion Channel Gating Kinetics Membrane Potentials Mutation Oocytes/drug effects,metabolism Peptides/antagonists & inhibitors,genetics,metabolism Potassium Channel Blockers Potassium Channels/drug effects,metabolism Recombinant Proteins/genetics,pharmacology Scorpion Venoms/genetics,pharmacology Shaker Superfamily of Potassium Channels Xenopus

Chemicals

Peptides Potassium Channel Blockers Potassium Channels Recombinant Proteins Scorpion Venoms Shaker B potassium channel polypeptide Shaker Superfamily of Potassium Channels Charybdotoxin

Authors & Affiliations

2 authors, click to expand affiliations / ORCID

Goldstein S A

Howard Hughes Medical Institute, Graduate Department of Biochemistry, Brandeis University, Waltham, MA 02254-9110.

Miller C

References (23)

23 references, click to expand

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Article Info

Journal

Biophysical journal

Abbr.

Biophys J

ISSN

0006-3495

DOI

10.1016/S0006-3495(93)81200-1

Published

1993-10-00

Pages

1613-9

Language

English

Region

United States

NLM ID

0370626

PMCID

PMC1225887

Subset

Grants

NIGMS NIH HHS · GM-31768 · United States

NHLBI NIH HHS · HL-02770 · United States

External Links

PubMed source DOI: 10.1016/S0006-3495(93)81200-1 PMC Full Text View journal details

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Mechanism of charybdotoxin block of a voltage-gated K+ channel.

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