title: Multiple subunits of a voltage-dependent potassium channel contribute to the binding site for tetraethylammonium.
abstract: RNAs encoding a wild-type (RBK1) and a mutant (RBK1(Y379V,V381T); RBK1*) subunit of voltage-dependent potassium channels were injected into Xenopus oocytes. When expressed separately, they made homotetrameric channels that differed about 100-fold in sensitivity to tetraethylammonium (TEA). Mixtures of channels having one, two, or three low affinity subunits were expressed by injecting various proportions of RBK1 and RBK1* RNAs. The affinity for TEA of these three channel species was deduced by fitting concentration-response curves for the inhibition of potassium currents. DNAs were also concatenated to construct a sequence that encoded two connected subunits, and channels that contained four, two, or no TEA-sensitive subunits were expressed. The results suggest that bound TEA interacts simultaneously with all four subunits.
authors.affiliation: Vollum Institute, Oregon Health Sciences University, Portland 97201.
authors.forename: M P
authors.initials: MP
authors.lastname: Kavanaugh
authors.forename: R S
authors.initials: RS
authors.lastname: Hurst
authors.forename: J
authors.initials: J
authors.lastname: Yakel
authors.forename: M D
authors.initials: MD
authors.lastname: Varnum
authors.forename: J P
authors.initials: JP
authors.lastname: Adelman
authors.forename: R A
authors.initials: RA
authors.lastname: North
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D066298:In Vitro Techniques; D046911:Macromolecular Substances; D008564:Membrane Potentials; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009838:Oligodeoxyribonucleotides / Q000737:chemistry; D009865:Oocytes; D015221:Potassium Channels / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D013329:Structure-Activity Relationship; D013757:Tetraethylammonium Compounds / Q000378:metabolism*; D014982:Xenopus laevis
chemical_list: D046911:Macromolecular Substances; D009838:Oligodeoxyribonucleotides; D015221:Potassium Channels; D011994:Recombinant Proteins; D013757:Tetraethylammonium Compounds