ON THE COVER
Lipid distribution around KCNQ1 potassium channel in coarsegrained simulations. Top: Extracellular and intracellular view of KCNQ1 (grey) embedded in a multi-component membrane. Bottom: Contour maps illustrating membrane component distribution around KCNQ1 in membranes enriched with polyunsaturated linoleic acid (LIN), saturated stearic acid (STE), or none of these (FA-FREE). Image © Yazdi et al., 2021. See http://doi.org/10.1085/jgp.202012850.
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Regional differences in arrhythmogenesis
JGP study shows that the subendocardium is more susceptible to spontaneous Ca2+ release events that can initiate arrhythmias, and this may be reduced by local CaMKII inhibition.
What FXYDs fix
Na,K ATPases are modulated by FXYD subunits. What do the FXYDs affect, how do they do it, and what are their physiological impacts?
Huntington’s disease skeletal muscle has altered T-tubules
Romer et al. explored T-tubules in skeletal muscle.
Unconventional voltage sensing in an inwardly rectifying potassium channel
Inwardly rectifying potassium channels are generally thought to achieve their physiological voltage dependence via an “extrinsic” mechanism involving voltage-dependent block by polyamines. A surprising finding of polyamine-independent gating of Kir4.1/Kir5.1 heteromeric channels suggests a mechanism of voltage dependence arising from interactions with permeating ions.
CaMKII inhibition reduces arrhythmogenic Ca2+ events in subendocardial cryoinjured rat living myocardial slices
Dries et al. show that injured myocardial slices from the subendocardium are more susceptible to spontaneous Ca2+ release events and whole-slice contractions than those from the subepicardium, and that this is reduced by CaMKII inhibition.
Identification of PUFA interaction sites on the cardiac potassium channel KCNQ1
The cardiac KCNQ1 channel is a promising anti-arrhythmic target. Yazdi et al. report on how PUFAs interact with two binding sites in KCNQ1 to trigger channel activation. These findings further our mechanistic understanding of how to modulate KCNQ1 activity.
The zinc-binding motif of TRPM7 acts as an oxidative stress sensor to regulate its channel activity
Inoue et al. use site-directed mutagenesis and reconstitution experiments to uncover critical residues within the zinc-binding motif of TRPM7 that are essential for the Mg2+-dependent regulation of the channel activity in conditions of oxidative stress.
Shaker-IR K+ channel gating in heavy water: Role of structural water molecules in inactivation
Szanto et al. use heavy water and Shaker-IR K+ channel mutants to establish that structural water molecules contribute to the inactivation of the selectivity filter of the channel. Their experimental evidence supports previous predictions stemming from molecular dynamics simulations.