The endoplasmic reticulum (ER) is a subcellular compartment playing a central role in
calcium storage and signaling. Disturbances of ER calcium homeostasis constitute a severe
form of stress interfering with central functions of this structure including the folding and
processing of newly synthesized membrane and secretory proteins. Blocking the folding and
processing reactions results in the accumulation of unfolded proteins forming potentially
toxic aggregates. To restore ER functioning, specific stress responses are activated one of …