min K channels form by assembly of at least 14 subunits

T. Tzounopoulos, H. R. Guy, S. Durell, J. P. Adelman, J. Maylie

Research output: Contribution to journalArticle

26 Scopus citations

Abstract

Injection of rain K mRNA into Xenopus oocytes results in expression of slowly activating voltage-dependent potassium channels, distinct from those induced by expression of other cloned potassium channels. The min K protein also differs in structure, containing only a single predicted transmembrane domain. While it has been demonstrated that all other cloned potassium channels form by association of four independent subunits, the number of min K monomers which constitute a functional channel is unknown. In rat min K, replacement of Ser-69 by Ala (S69A) causes a shift in the current-voltage (I- V) relationship to more depolarized potentials; currents are not observed at potentials negative to 0 reV. To determine the subunit stoichiometry of min K channels, wild-type and S69A subunits were coexpressed. Injections of a constant amount of wild-type mRNA with increasing amounts of S69A mRNA led to potassium currents of decreasing amplitude upon voltage commands to -20 mV. Applying a binomial distribution to the reduction of current amplitudes as a function of the different coinjection mixtures yielded a subunit stoichiometry of at least 14 monomers for each functional rain K channel. A model is presented for how rain K subunits may form a channel.

Original languageEnglish (US)
Pages (from-to)9593-9597
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume92
Issue number21
DOIs
StatePublished - Oct 10 1995

ASJC Scopus subject areas

  • General

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