The N-linker region of hERG1a upregulates hERG1b potassium channels.
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JournalJournal of Biological Chemistry
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AbstractA major physiological role of hERG1 (human Ether-á-go-go-Related Gene) potassium channels is to repolarize cardiac action potentials. Two isoforms, hERG1a and hERG1b, associate to form the native cardiac IKr current in vivo. Inherited mutations in hERG1a or hERG1b cause prolonged cardiac repolarization, Long QT Syndrome and sudden death arrhythmia. hERG1a subunits assemble with and enhance the number of hERG1b subunits at the plasma membrane, but the mechanism for the increase in hERG1b by hERG1a is not well understood. Here, we report that the hERG1a N-terminal region expressed in trans with hERG1b markedly increased hERG1b currents and increased biotin-labelled hERG1b protein at the membrane surface. hERG1b channels with a deletion of the N-terminal 1b domain did not have a measurable increase in current or biotinylated protein when co-expressed with hERG1a N-terminal regions, indicating that the 1b domain was required for the increase in hERG1b. Using a biochemical pull-down interaction assay and a FRET hybridization experiment, we detected a direct interaction between the hERG1a N-terminal region and the hERG1b N-terminal region. Using engineered deletions and alanine mutagenesis, we identified a short span of amino acids at positions 216-220 within the hERG1a 'N-linker' region that were necessary for the upregulation of hERG1b. We propose that direct structural interactions between the hERG1a N-linker region and the hERG1b 1b domain increase hERG1b at the plasma membrane. Mechanisms regulating hERG1a and hERG1b are likely critical for cardiac function, may be disrupted by LQTS mutants and serve as potential targets for therapeutics.
Data AvailibilityExemplar current recordings, fluorescence spectroscopy traces and Western blot images are all located within the manuscript. All data are contained in plots within the manuscript. Any additional raw data used to generate plots can be requested from Dr. Matt Trudeau (firstname.lastname@example.org).
Rights/TermsCopyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.
Long QT syndrome
biochemical pull-down interaction assay
Identifier to cite or link to this itemhttp://hdl.handle.net/10713/19348
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