Animal physiology depends on degenerin, epithelial sodium, and acid-sensing ion channels (DEG/ENaC/ASICs). By measuring the sensitivity of three C. elegans DEG/ENaC/ASICs to amiloride analogs and NSAIDs, Fechner et al. show that individual channels have distinct pharmacological footprints.

Martinez-Espinosa et al. show that FGF14 and the voltage-dependent Na+ channel Nav1.3 are the main regulators of rapidly inactivating currents and Nav channel availability in mouse adrenal chromaffin cells. Their results uncover a role for FGF14 in regulating Nav channel function.

Cardiac myosin-binding protein C (cMyBP-C) is thought to regulate cardiac muscle and heart contraction. Hanft et al. show that cMyBP-C phosphorylation regulates length dependence of power output in murine permeabilized cardiac myocytes, which translates to in vivo Frank–Starling relationships.

Martinez-Espinosa et al. show that fast and slow recovery of voltage-dependent Na+ (Nav) channels in rat adrenal chromaffin cells depends on two independent inactivation pathways. Competition between these pathways regulates changes in Nav channel availability.

Bunch et al. describe a new assay to rapidly evaluate binding of cMyBP-C to F-actin (with or without tropomyosin) in solution. Changes in labeled actin fluorescence lifetime due to cMyBP-C phosphorylation and/or HCM mutations were consistent with measurements obtained using cosedimentation assays.

In this study, Kawai et al. address the role of inorganic phosphate in muscle cross-bridge kinetics using a subcellular structure called myofibrils. They demonstrate that phosphate binding is a key determinant of oscillatory work and suggest that it may also compete with ATP for binding to the myosin head.

Giles et al. show that the phosphorylation status of cardiac myosin-binding protein-C (cMyBP-C) modulates Ca2+ activation–dependent unloaded shortening velocity of skinned myocardium. The results suggest that cMyBP-C phosphorylation regulates cooperative binding of myosin to actin, and thus the activation state of the thin filament.