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Proc Natl Acad Sci U S A. 2013 Aug 6;110(32):13180-5. doi: 10.1073/pnas.1305167110. Epub 2013 Jul 16.

Kv7.1 ion channels require a lipid to couple voltage sensing to pore opening.

Author information

1
Department of Biomedical Engineering, Cardiac Bioelectricity and Arrhythmia Center, Washington University in St. Louis, St. Louis, MO 63130-4862, USA.

Abstract

Voltage-gated ion channels generate dynamic ionic currents that are vital to the physiological functions of many tissues. These proteins contain separate voltage-sensing domains, which detect changes in transmembrane voltage, and pore domains, which conduct ions. Coupling of voltage sensing and pore opening is critical to the channel function and has been modeled as a protein-protein interaction between the two domains. Here, we show that coupling in Kv7.1 channels requires the lipid phosphatidylinositol 4,5-bisphosphate (PIP2). We found that voltage-sensing domain activation failed to open the pore in the absence of PIP2. This result is due to loss of coupling because PIP2 was also required for pore opening to affect voltage-sensing domain activation. We identified a critical site for PIP2-dependent coupling at the interface between the voltage-sensing domain and the pore domain. This site is actually a conserved lipid-binding site among different K(+) channels, suggesting that lipids play an important role in coupling in many ion channels.

KEYWORDS:

KCNQ; channelopathy; electromechanical coupling; phosphoinositide; voltage channel

PMID:
23861489
PMCID:
PMC3740903
DOI:
10.1073/pnas.1305167110
[Indexed for MEDLINE]
Free PMC Article

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