Proteasome activity can be regulated through its accumulation in cytoplasmic proteasome storage granules (PSGs). In yeast, PSGs assemble when glucose or other carbon sources are low, and this is thought to protect the proteasome during stress conditions. Peters et al. show that a functional vacuolar ATPase (v-ATPase) proton pump is necessary for normal kinetics of PSG formation and disassembly. Lower cytosolic pH due to impaired v-ATPase function resulted in faster-forming granules and slow release of the proteasome from the granules. Interestingly, low pH also promoted the formation of actin bodies, another type of yeast cytoplasmic granule that assembles during starvation. Thus, the authors propose that intracellular pH functions as a cellular signal for glucose sensing and granule formation.