title: Obligatory heterotetramerization of three previously uncharacterized Kv channel alpha-subunits identified in the human genome.
abstract: Voltage-gated K(+) channels control excitability in neuronal and various other tissues. We identified three unique alpha-subunits of voltage-gated K(+)-channels in the human genome. Analysis of the full-length sequences indicated that one represents a previously uncharacterized member of the Kv6 subfamily, Kv6.3, whereas the others are the first members of two unique subfamilies, Kv10.1 and Kv11.1. Although they have all of the hallmarks of voltage-gated K(+) channel subunits, they did not produce K(+) currents when expressed in mammalian cells. Confocal microscopy showed that Kv6.3, Kv10.1, and Kv11.1 alone did not reach the plasma membrane, but were retained in the endoplasmic reticulum. Yeast two-hybrid experiments failed to show homotetrameric interactions, but showed interactions with Kv2.1, Kv3.1, and Kv5.1. Co-expression of each of the previously uncharacterized subunits with Kv2.1 resulted in plasma membrane localization with currents that differed from typical Kv2.1 currents. This heteromerization was confirmed by co-immunoprecipitation. The Kv2 subfamily consists of only two members and uses interaction with "silent subunits" to diversify its function. Including the subunits described here, the "silent subunits" represent one-third of all Kv subunits, suggesting that obligatory heterotetramer formation is more widespread than previously thought.
authors.affiliation: Laboratory for Molecular Biophysics, Physiology, and Pharmacology, Department of Biomedical Sciences, University of Antwerp (UIA), Universiteitsplein 1, T4.21 B2610 Antwerp, Belgium.
authors.forename: N
authors.initials: N
authors.lastname: Ottschytsch
authors.forename: A
authors.initials: A
authors.lastname: Raes
authors.forename: D
authors.initials: D
authors.lastname: Van Hoorick
authors.forename: D J
authors.initials: DJ
authors.lastname: Snyders
mesh_terms: D000595:Amino Acid Sequence; D051638:Ether-A-Go-Go Potassium Channels; D015894:Genome, Human; D006801:Humans; D046911:Macromolecular Substances; D008564:Membrane Potentials; D008969:Molecular Sequence Data; D018408:Patch-Clamp Techniques; D010802:Phylogeny; D015221:Potassium Channels / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D024642:Potassium Channels, Voltage-Gated; D021122:Protein Subunits; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D051669:Shab Potassium Channels
chemical_list: D051638:Ether-A-Go-Go Potassium Channels; C496988:KCNB1 protein, human; C450424:KCNG3 protein, human; C496884:KCNH1 protein, human; D046911:Macromolecular Substances; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; D021122:Protein Subunits; D051669:Shab Potassium Channels