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XB-ART-43798
Proc Natl Acad Sci U S A 2011 May 31;10822:9095-100. doi: 10.1073/pnas.1100872108.
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KCNE1 enhances phosphatidylinositol 4,5-bisphosphate (PIP2) sensitivity of IKs to modulate channel activity.

Li Y , Zaydman MA , Wu D , Shi J , Guan M , Virgin-Downey B , Cui J .


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Phosphatidylinositol 4,5-bisphosphate (PIP(2)) is necessary for the function of various ion channels. The potassium channel, I(Ks), is important for cardiac repolarization and requires PIP(2) to activate. Here we show that the auxiliary subunit of I(Ks), KCNE1, increases PIP(2) sensitivity 100-fold over channels formed by the pore-forming KCNQ1 subunits alone, which effectively amplifies current because native PIP(2) levels in the membrane are insufficient to activate all KCNQ1 channels. A juxtamembranous site in the KCNE1 C terminus is a key structural determinant of PIP(2) sensitivity. Long QT syndrome associated mutations of this site lower PIP(2) affinity, resulting in reduced current. Application of exogenous PIP(2) to these mutants restores wild-type channel activity. These results reveal a vital role of PIP(2) for KCNE1 modulation of I(Ks) channels that may represent a common mechanism of auxiliary subunit modulation of many ion channels.

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Species referenced: Xenopus laevis
Genes referenced: kcne1 kcnq1

References [+] :
Abbott, MiRP1 forms IKr potassium channels with HERG and is associated with cardiac arrhythmia. 1999, Pubmed, Xenbase