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Channels (Austin). 2017 Nov 2;11(6):686-695. doi: 10.1080/19336950.2017.1388478. Epub 2017 Nov 17.

Ca2+-Calmodulin and PIP2 interactions at the proximal C-terminus of Kv7 channels.

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a Department of Physiology & Pharmacology , Sackler Faculty of Medicine and Sagol School of Neurosciences, Tel Aviv University , Tel Aviv , Israel.
b Department of Biochemistry & Molecular Biology , George S. Wise Faculty of Life Sciences, Institute of Structural Biology, Tel Aviv University , Tel Aviv , Israel.
c Department of Pharmaceutical Sciences , Northeastern University , Boston , MA , USA.
d Laboratory of Structural Physiology, Department of Physiology & Pharmacology , Sackler Faculty of Medicine, Tel Aviv University , Tel Aviv , Israel.


In the heart, co-assembly of Kv7.1 with KCNE1 produces the slow IKS potassium current, which repolarizes the cardiac action potential and mutations in human Kv7.1 and KCNE1 genes cause cardiac arrhythmias. The proximal Kv7.1 C-terminus binds calmodulin (CaM) and phosphatidylinositol-4,5-bisphosphate (PIP2) and recently we revealed the competition of PIP2 with the calcified CaM N-lobe to a previously unidentified site in Kv7.1 helix B, also known to harbor a LQT mutation. Data indicated that PIP2 and Ca2+-CaM perform the same function on IKS channel gating to stabilize the channel open state. Here we show that similar features were observed for Kv7.1 currents expressed alone. We also find that conservation of homologous residues in helix B of other Kv7 subtypes confer similar competition of Ca2+-CaM with PIP2 binding to their proximal C-termini and suggest that PIP2-CaM interactions converge to Kv7 helix B to modulates channel activity in a Kv7 subtype-dependent manner.


KCNQ; Kv7; PIP2; Potassium channel; calmodulin

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