Skeletal muscle oxidative capacity and fatigue resistance can be improved with endurance training, but the mechanism is not fully understood. Ivarsson et al. find that the signaling pathway that increases fatigue resistance in muscle is triggered by a mild Ca²⁺ leak from the sarcoplasmic reticulum.

Receptors convert agonist-binding energy into conformational change. Nayak et al. describe a new agonist trait, efficiency, as the fraction of binding energy transformed into the mechanical work of conformational change and suggest that it is a general attribute of agonist action at receptor-binding sites.

The intracellular amino and carboxyl termini of the P2X1 receptor associate to form a cytoplasmic cap on the open state. Fryatt et al. use cysteine-reactive cross linking and molecular modeling to demonstrate structural organization of the intracellular termini in the apo and desensitized states.