Compartmentation of membrane processes and nucleotide dynamics in diffusion-restricted cardiac cell microenvironment

► Transducers and effectors are co-localized for vectorial response to environmental signals. ► Membrane macromolecular units are secluded by diffusion barriers limiting metabolite mobility. ► Membrane complexes comprise local nucleotide sensors able to adjust energy demand. ► Phosphotransfer reactions shunt diffusion barriers and actively modulate nucleotide signals. ► Diffusion barriers permit transmission of only sustained changes in bulk energetics.