Subunit stoichiometry of a mammalian K+ channel determined by construction of multimeric cDNAs.
The subunit stoichiometry of the mammalian K+ channel KV1.1 (RCK1) was examined by linking together the coding sequences of 2-5 K+ channel subunits in a single open reading frame and tagging the expression of individual subunits with a mutation (Y379K or Y379R) that altered the sensitivity of the channel to block by external tetraethylammonium ion. Two lines of evidence argue that these constructs lead to K+ channel expression only through the formation of functional tetramers. First, currents expressed by tetrameric constructs containing a single mutant subunit have a sensitivity to tetraethylammonium that is well fitted by a single site binding isotherm. Second, a mutant subunit (Y379K) that expresses only as part of a heteromultimer contributes to the expression of functional channels when coexpressed with a trimeric construct but not a tetrameric construct.
Liman
E R
ER
Department of Cellular and Molecular Physiology, Harvard Medical School, Boston, Massachusetts 02115.
Tytgat
J
J
Hess
P
P
D000595:Amino Acid Sequence; D000818:Animals; D004247:DNA / Q000737:chemistry* / Q000235:genetics; D004553:Electric Conductivity; D015870:Gene Expression; D005822:Genetic Vectors; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009865:Oocytes / Q000378:metabolism; D015221:Potassium Channels / Q000737:chemistry* / Q000235:genetics / Q000502:physiology; D019789:Tetraethylammonium; D013757:Tetraethylammonium Compounds / Q000494:pharmacology; D013816:Thermodynamics; D014981:Xenopus
D046911:Macromolecular Substances; D015221:Potassium Channels; D013757:Tetraethylammonium Compounds; D019789:Tetraethylammonium; D004247:DNA