Interactions Between The C-terminus of Kv1.5 and Kvβ Regulate Pyridine Nucleotide-Dependent Changes in Channel Gating
Document Type
Article
Publication Date
2012
Keywords
Voltage-gated Potassium Channel, Whole-cell Patch Clamp, Kvβ, Pyridine Nucleotides, Redox, Aldo-keto Reductase
Digital Object Identifier (DOI)
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.
Was this content written or created while at USF?
Yes
Citation / Publisher Attribution
Pflügers Archiv - European Journal of Physiology, v. 463, p. 799-818
Scholar Commons Citation
Tipparaju, Srinicas M.; Li, Xiao-Ping; Kilfoil, Peter J.; Xue, Bin; Uversky, Vladimir N.; Bhatnagar, Aruni; and Barski, Oleg A., "Interactions Between The C-terminus of Kv1.5 and Kvβ Regulate Pyridine Nucleotide-Dependent Changes in Channel Gating" (2012). Molecular Medicine Faculty Publications. 509.
https://digitalcommons.usf.edu/mme_facpub/509
