Surface expression and subunit specific control of steady protein levels by the Kv7.2 helix A-B linker

PLoS One. 2012;7(10):e47263. doi: 10.1371/journal.pone.0047263. Epub 2012 Oct 24.

Abstract

Kv7.2 and Kv7.3 are the main components of the neuronal voltage-dependent M-current, which is a subthreshold potassium conductance that exerts an important control on neuronal excitability. Despite their predominantly intracellular distribution, these channels must reach the plasma membrane in order to control neuronal activity. Thus, we analyzed the amino acid sequence of Kv7.2 to identify intrinsic signals that may control its surface expression. Removal of the interlinker connecting helix A and helix B of the intracellular C-terminus produces a large increase in the number of functional channels at the plasma membrane. Moreover, elimination of this linker increased the steady-state amount of protein, which was not associated with a decrease of protein degradation. The magnitude of this increase was inversely correlated with the number of helix A - helix B linkers present in the tetrameric channel assemblies. In contrast to the remarkable effect on the amount of Kv7.2 protein, removal of the Kv7.2 linker had no detectable impact on the steady-state levels of Kv7.3 protein.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • HEK293 Cells
  • Humans
  • KCNQ2 Potassium Channel / chemistry
  • KCNQ2 Potassium Channel / metabolism*
  • KCNQ2 Potassium Channel / physiology
  • Microscopy, Confocal
  • Molecular Sequence Data
  • Patch-Clamp Techniques
  • Xenopus

Substances

  • KCNQ2 Potassium Channel

Grants and funding

This work was supported by grants from the VII European framework program managed by the Fondo de Investigaciones Sanitarias (PI071316), from the Spanish Ministry of Education (BFU2009-07581 and SAF2006-1450), the Spanish Ion Channel Initiative Consolider project (CSD2008-00005), and the Basque Government (SAIOTEK SA-2006/00023). A. Alaimo was partially funded by Fundación Biofísica Bizkaia. PA and JFO held a FPI fellowship from the Spanish Ministry of Science and Innovation (BES-2008-002314). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.