title: YKC1 encodes the depolarization-activated K+ channel in the plasma membrane of yeast.
abstract: Our previous patch-clamp studies showed that depolarization activates a K(+)-specific current in the plasma membrane of the budding yeast, Saccharomyces cerevisiae [Gustin et al. (1986) Science 233, 1195-1197]. The Yeast Genome Sequencing Project has now uncovered on the left arm of chromosome X an open reading frame (ORF) that predicts a 77-kDa protein reminiscent of a shaker-like alpha subunit with 6 membrane spans followed by a subunit with 2 spans. We found that deleting this ORF removes the yeast K+ current. Furnishing the ORF from plasmids restores or even greatly amplifies this current. These manipulations have no effects on the 40-pS mechanosensitive conductance also native to this membrane. Thus, this ORF, named YKC1 here, likely encodes a structure for the K(+)-specific channel of the yeast plasma membrane. This and other K+ channel subunits are compared and the possible uses of this gene in research are discussed. YKC1 has recently been shown by others to induce in frog oocytes a K+ current. Its activation is coupled to EK+ and its outward rectification depends on external divalent cations. We found the YKC1 channel in its native membrane activates at low voltages largely independent of EK+ and it remains so despite removal of divalents by chelation.
authors.affiliation: Laboratory of Molecular Biology, University of Wisconsin, Madison 53706, USA.
authors.forename: X L
authors.initials: XL
authors.lastname: Zhou
authors.forename: B
authors.initials: B
authors.lastname: Vaillant
authors.forename: S H
authors.initials: SH
authors.lastname: Loukin
authors.forename: C
authors.initials: C
authors.lastname: Kung
authors.forename: Y
authors.initials: Y
authors.lastname: Saimi
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002462:Cell Membrane / Q000502:physiology; D017931:DNA Primers; D004330:Drosophila; D005800:Genes, Fungal; D008564:Membrane Potentials; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D018408:Patch-Clamp Techniques; D010957:Plasmids; D015221:Potassium Channels / Q000737:chemistry / Q000235:genetics* / Q000502:physiology*; D017433:Protein Structure, Secondary; D015183:Restriction Mapping; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000502:physiology*; D017386:Sequence Homology, Amino Acid
chemical_list: D017931:DNA Primers; D015221:Potassium Channels