Hanna et al. generate two conditional mouse models of embryonic loss of FKBP12 in cardiomyocytes. Their findings show a progressive development of dilated cardiomyopathy, cardiac oxidative stress, and calcium leak, and suggest a role for FKBP12 in embryonic cardiac muscle.

In this work, Liu and Bezanilla describe a voltage-gated sodium channel mutant that removes fast inactivation while the fast inactivation particle, the IFM motif, remains bound. This work indicates that fast inactivation requires further conformational changes in addition to IFM motif binding.

In macroscopic electrophysiological experiments, the maximal probability of being active (P_A,max) is typically determined by comparing the response to a saturating concentration of the test agonist to the response to a reference agonist. Germann et al. present an approach to estimate P_A,max at subsaturating concentrations of test agonist.

At synapses, NMDA receptors (NMDAR) convert presynaptically released glutamate into a synaptic signal. Here, He and Wollmuth define the impact of various environmental factors and GluN2 subunit composition on the efficiency of rapid glutamate-induced channel opening.

Murthy and Baker propose a stochastic two-state thermodynamic model of muscle contraction that provides a novel interpretation of muscle mechanics and chemistry, in which the entropy of an ensemble of molecules contributes to the energetics and mechanics of the contractile system.

Bacterial TAXI-TRAP transporters are widespread but poorly understood. Davies et al. characterize a TAXI from Vibrio cholerae, revealing its glutamate specificity, binding determinants, and unusual membrane component. As glutamate is a key metabolite in pathogens, glutamate transporters are potential therapeutic targets.

The activation of DRP1 during ischemia-reperfusion results in mitochondrial fragmentation, which is known to be a key trigger of cardiac injuries. Dubois et al. evaluate whether preconditioning with exercise training can limit the activation of DRP1 and excessive mitochondrial fragmentation during myocardial ischemia-reperfusion.