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Updated: Feb 7, 2026

An In Vitro Single-Molecule Imaging Assay for the Analysis of Cap-Dependent Translation Kinetics
Published on: September 15, 2020
Single channel kinetic analysis of the cAMP effect on IKs mutants, S209F and S27D/S92D
Emely Thompson1, Jodene Eldstrom1, David Fedida1
1a Department of Anesthesiology, Pharmacology and Therapeutics , University of British Columbia , Vancouver , BC , Canada.
Abstract:
The IKs current is important in the heart's response to sympathetic stimulation. β-adrenergic stimulation increases the amount of IKs and creates a repolarization reserve that shortens the cardiac action potential duration. We have recently shown that 8-CPT-cAMP, a membrane-permeable cAMP analog, changes the channel kinetics and causes it to open more quickly and more often, as well as to higher subconductance levels, which produces an increase in the IKs current. The mechanism proposed to underlie these kinetic changes is increased activation of the voltage sensors. The present study extends our previous work and shows detailed subconductance analysis of the effects of 8-CPT-cAMP on an enhanced gating mutant (S209F) and on a double pseudo-phosphorylated IKs channel (S27D/S92D). 8-CPT-cAMP still produced kinetic changes in S209F + KCNE1, further enhancing gating, while S27D/S92D + KCNE1 showed no significant response to 8-CPT-cAMP, suggesting that these last two mutations fully recapitulate the effect of channel phosphorylation by cAMP.
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