title: Independent movement of the voltage sensors in KV2.1/KV6.4 heterotetramers.
abstract: Heterotetramer voltage-gated K+(KV) channels KV2.1/KV6.4 display a gating charge-voltage (QV) distribution composed by two separate components. We use state dependent chemical accessibility to cysteines substituted in either KV2.1 or KV6.4 to assess the voltage sensor movements of each subunit. By comparing the voltage dependences of chemical modification and gating charge displacement, here we show that each gating charge component corresponds to a specific subunit forming the heterotetramer. The voltage sensors from KV6.4 subunits move at more negative potentials than the voltage sensors belonging to KV2.1 subunits. These results indicate that the voltage sensors from the tetrameric channels move independently. In addition, our data shows that 75% of the total charge is attributed to KV2.1, while 25% to KV6.4. Thus, the most parsimonious model for KV2.1/KV6.4 channels' stoichiometry is 3:1.
authors.affiliation: Laboratory for Molecular Biophysics, Physiology and Pharmacology, Department for Biomedical Sciences, University of Antwerp, Antwerp, Belgium.|Molecular Neurophysiology Section, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA.
authors.forename: Elke
authors.initials: E
authors.lastname: Bocksteins
authors.affiliation: Laboratory for Molecular Biophysics, Physiology and Pharmacology, Department for Biomedical Sciences, University of Antwerp, Antwerp, Belgium.
authors.forename: Dirk J
authors.initials: DJ
authors.lastname: Snyders
authors.affiliation: Molecular Neurophysiology Section, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA.
authors.forename: Miguel
authors.initials: M
authors.lastname: Holmgren
mesh_terms: D000595:Amino Acid Sequence; D002460:Cell Line; D002478:Cells, Cultured; D006801:Humans; D015640:Ion Channel Gating; D008564:Membrane Potentials; D055503:Protein Multimerization; D021122:Protein Subunits; D051669:Shab Potassium Channels / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: D021122:Protein Subunits; D051669:Shab Potassium Channels