Independent movement of the voltage sensors in KV2.1/KV6.4 heterotetramers

Elke Bocksteins; Dirk J Snyders; Miguel Holmgren

doi:10.1038/srep41646

Independent movement of the voltage sensors in K_V2.1/K_V6.4 heterotetramers

Sci Rep. 2017 Jan 31:7:41646. doi: 10.1038/srep41646.

Authors

Elke Bocksteins^{1

2}, Dirk J Snyders¹, Miguel Holmgren²

Affiliations

¹ Laboratory for Molecular Biophysics, Physiology and Pharmacology, Department for Biomedical Sciences, University of Antwerp, Antwerp, Belgium.
² Molecular Neurophysiology Section, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA.

Abstract

Heterotetramer voltage-gated K⁺ (K_V) channels K_V2.1/K_V6.4 display a gating charge-voltage (Q_V) distribution composed by two separate components. We use state dependent chemical accessibility to cysteines substituted in either K_V2.1 or K_V6.4 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 K_V6.4 subunits move at more negative potentials than the voltage sensors belonging to K_V2.1 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 K_V2.1, while 25% to K_V6.4. Thus, the most parsimonious model for K_V2.1/K_V6.4 channels' stoichiometry is 3:1.

Publication types

Research Support, N.I.H., Intramural
Research Support, Non-U.S. Gov't

MeSH terms

Amino Acid Sequence
Cell Line
Cells, Cultured
Humans
Ion Channel Gating*
Membrane Potentials
Protein Multimerization*
Protein Subunits
Shab Potassium Channels / chemistry*
Shab Potassium Channels / genetics
Shab Potassium Channels / metabolism*

Substances

Protein Subunits
Shab Potassium Channels