- Doublet stimulation increases on Ca2+ and force
High-frequency paired stimuli used to initiate a tetanus result in increased force and rate of force development in skeletal muscle. Bakker et al. investigate this mechanism and find that doublet stimulation increases the amount of Ca2+ bound to troponin C, resulting in rapid force development.
- Voltage-gate coupling in truncated BK channels
Both cellular depolarization and intracellular Ca2+ can gate open large conductance Ca2+-activated K+ channels. Zhang et al. show that the intracellular gating ring, which forms the Ca2+-sensing machinery of the channel, is also required for activated voltage sensors to effectively gate open the pore.
- CaM regulates Na+ channel persistent current
The molecular mechanisms controlling “persistent” current through voltage-gated Na+ channels are poorly understood. Yan et al. show that apocalmodulin binding to the intracellular C-terminal domain limits persistent Na+ flux and accelerates inactivation across the voltage-gated Na+ channel family.