Endoplasmic reticulum: ER stress regulates mitochondrial bioenergetics

► The ER is the site of synthesis, folding and processing of secreted proteins, and is also the main reservoir of intracellular calcium. ► Protein misfolding activates ER signaling cascades that modulate the function of other organelles. ► The ER physically interacts with mitochondria. ► Calcium release from ER stores stimulates mitochondrial bioenergetics as an adaptive response during the early phases of ER stress. ► Prolonged, severe ER stress can lead to pathological changes in cell metabolism and eventually apoptosis.