Cover picture: KcsA is a bacterial potassium channel gated by protons, which open and close the intracellular activation gate. Using labeled histidine residues located in key regions of the channel, NMR spectroscopy reveals that KcsA adopts multiple open and closed conformations in lipid bicelles, as observed by slow exchange between distinct functional states at varying pH (see Research Article by Kim et al., 119–132).
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Conformational heterogeneity in closed and open states of the KcsA potassium channel in lipid bicelles
KcsA is a potassium channel that is gated open and closed by changes in pH. Kim et al. find that at least two conformational states exist for both closed and open KcsA channels using solution NMR.
Biophysical characterization of the honeybee DSC1 orthologue reveals a novel voltage-dependent Ca2+ channel subfamily: CaV4
Insect DSC1 channels have sequences that are intermediate between voltage-gated Na+ and Ca2+ channels but have hitherto been classified as the former. Gosselin-Badaroudine et al. clone and characterize honeybee DSC1, revealing high selectivity for Ca2+ and suggesting reclassification of DSC1 homologues as Ca2+ channels.
The α2δ-1 subunit remodels CaV1.2 voltage sensors and allows Ca2+ influx at physiological membrane potentials
Voltage-sensing domains (VSDs) in voltage-gated calcium channels sense the potential difference across membranes and interact with the pore to open it. Savalli et al. find that the accessory subunit α2δ-1 increases the sensitivity of VSDs I–III and also their efficiency of coupling to the pore.
Principal cells regulate the ionic environment of the epididymal lumen via unknown mechanisms. Gao et al. use electrophysiological and pharmacological tools to characterize rat principal cells and reveal a TRPV6-mediated calcium conductance and TMEM16A-mediated calcium-activated chloride conductance.