Interactions between the C-terminus of Kv1.5 and Kvβ regulate pyridine nucleotide-dependent changes in channel gating
- 17 March 2012
- journal article
- research article
- Published by Springer Science and Business Media LLC in Pflügers Archiv - European Journal of Physiology
- Vol. 463 (6), 799-818
- https://doi.org/10.1007/s00424-012-1093-z
Abstract
Voltage-gated potassium (Kv) channels are tetrameric assemblies of transmembrane Kv proteins with cytosolic N- and C-termini. The N-terminal domain of Kv1 proteins binds to β-subunits, but the role of the C-terminus is less clear. Therefore, we studied the role of the C-terminus in regulating Kv1.5 channel and its interactions with Kvβ-subunits. When expressed in COS-7 cells, deletion of the C-terminal domain of Kv1.5 did not affect channel gating or kinetics. Coexpression of Kv1.5 with Kvβ3 increased current inactivation, whereas Kvβ2 caused a hyperpolarizing shift in the voltage dependence of current activation. Inclusion of NADPH in the patch pipette solution accelerated the inactivation of Kv1.5-Kvβ3 currents. In contrast, NADP^+ decreased the rate and the extent of Kvβ3-induced inactivation and reversed the hyperpolarizing shift in the voltage dependence of activation induced by Kvβ2. Currents generated by Kv1.5ΔC+Kvβ3 or Kv1.5ΔC+Kvβ2 complexes did not respond to changes in intracellular pyridine nucleotide concentration, indicating that the C-terminus is required for pyridine nucleotide-dependent interactions between Kvβ and Kv1.5. A glutathione- S -transferase (GST) fusion protein containing the C-terminal peptide of Kv1.5 did not bind to apoKvβ2, but displayed higher affinity for Kvβ2:NADPH than Kvβ2:NADP^+. The GST fusion protein also precipitated Kvβ proteins from mouse brain lysates. Pull-down experiments, structural analysis and electrophysiological data indicated that a specific region of the C-terminus (Arg543-Val583) is required for Kvβ binding. These results suggest that the C-terminal domain of Kv1.5 interacts with β-subunits and that this interaction is essential for the differential regulation of Kv currents by oxidized and reduced nucleotides.Keywords
This publication has 43 references indexed in Scilit:
- PONDR-FIT: A meta-predictor of intrinsically disordered amino acidsBiochimica et Biophysica Acta (BBA) - Proteins and Proteomics, 2010
- Catalytic Mechanism and Substrate Specificity of the β-Subunit of the Voltage-Gated Potassium ChannelBiochemistry, 2008
- Functional Coupling between the Kv1.1 Channel and Aldoketoreductase Kvβ1Published by Elsevier BV ,2008
- The Aldo-Keto Reductase Superfamily and its Role in Drug Metabolism and DetoxificationDrug Metabolism Reviews, 2008
- Mining α-Helix-Forming Molecular Recognition Features with Cross Species Sequence AlignmentsBiochemistry, 2007
- Clustal W and Clustal X version 2.0Bioinformatics, 2007
- Intrinsic disorder in the C-terminal domain of the Shaker voltage-activated K + channel modulates its interaction with scaffold proteinsProceedings of the National Academy of Sciences of the United States of America, 2007
- NADPH binding to β-subunit regulates inactivation of voltage-gated K+ channelsBiochemical and Biophysical Research Communications, 2007
- Modulation of Voltage-dependent Shaker Family Potassium Channels by an Aldo-Keto Reductase*Journal of Biological Chemistry, 2006
- Coupled Folding and Binding with α-Helix-Forming Molecular Recognition ElementsBiochemistry, 2005