Determination of the subunit stoichiometry of a voltage-activated potassium channel.
The voltage-activated K+, Na+ and Ca2+ channels are responsible for the generation and propagation of electrical signals in cell membranes. The K+ channels are multimeric membrane proteins formed by the aggregation of an unknown number of independent subunits. By studying the interaction of a scorpion toxin with coexpressed wild-type and toxin-insensitive mutant Shaker K+ channels, the subunit stoichiometry can be determined. The Shaker K+ channel is found to have a tetrameric structure. This is consistent with the sequence relationship between a K+ channel and each of the four internally homologous repeats of Na+ and Ca2+ channels.
MacKinnon
R
R
Department of Cellular and Molecular Physiology, Harvard Medical School, Boston, Massachusetts 02115.
D000818:Animals; D018999:Charybdotoxin; D008564:Membrane Potentials; D008565:Membrane Proteins / Q000502:physiology; D009154:Mutation; D015221:Potassium Channels / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D012313:RNA / Q000378:metabolism; D012604:Scorpion Venoms / Q000633:toxicity; D014981:Xenopus
D008565:Membrane Proteins; D015221:Potassium Channels; D012604:Scorpion Venoms; D018999:Charybdotoxin; D012313:RNA