Small conductance Ca2+-activated K+ channels and calmodulin
Small conductance Ca 2+ -activated K + channels (SK channels) contribute to the long lasting afterhyperpolarization (AHP) that follows an action potential in many central neurones. The biophysical and pharmacological attributes of cloned SK channels strongly suggest that one or more of them underlie...
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Published in | The Journal of physiology Vol. 554; no. 2; pp. 255 - 261 |
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Main Authors | , , , , |
Format | Journal Article |
Language | English |
Published |
9600 Garsington Road , Oxford , OX4 2DQ , UK
The Physiological Society
15.01.2004
Blackwell Publishing Ltd Blackwell Science Inc |
Subjects | |
Online Access | Get full text |
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Summary: | Small conductance Ca 2+ -activated K + channels (SK channels) contribute to the long lasting afterhyperpolarization (AHP) that follows an action potential in many
central neurones. The biophysical and pharmacological attributes of cloned SK channels strongly suggest that one or more of
them underlie the medium component of the AHP that regulates interspike interval and plays an important role in setting tonic
firing frequency. The cloned SK channels comprise a distinct subfamily of K + channels. Heterologously expressed SK channels recapitulate the biophysical and pharmacological hallmarks of native SK channels,
being gated solely by intracellular Ca 2+ ions with no voltage dependence to their gating, small unitary conductance values and sensitivity to the bee venom peptide
toxin, apamin. Molecular, biochemical and electrophysiological studies have revealed that Ca 2+ gating in SK channels is due to heteromeric assembly of the SK α pore-forming subunits with calmodulin (CaM). Ca 2+ binding to the N-terminal EâF hands of CaM is responsible for SK channel gating. Crystallographic studies suggest that SK
channels gate as a dimer-of-dimers, and that the physical gate of SK channels resides at or near the selectivity filter of
the channels. In addition, Ca 2+ -independent interactions between the SK channel α subunits and CaM are necessary for proper membrane trafficking. |
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Bibliography: | This report was presented at The Journal of Physiology Symposium on Ion Channels: Their Structure, Function and Control, Fukuoka, Kyushu, Japan, 24 March 2003. It was commissioned by the Editorial Board and reflects the views of the author. ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-3 content type line 23 ObjectType-Review-1 |
ISSN: | 0022-3751 1469-7793 |
DOI: | 10.1113/jphysiol.2003.049072 |