Sensing cellular stress through STIM proteins.

In response to decreasing Ca2+ levels in the endoplasmic reticulum, STIM proteins couple with Orai channels in the plasma membrane, leading to Ca2+ influx into the cell. In addition to Ca2+-related endoplasmic reticulum stress, STIM proteins are emerging as general stress sensors that react to multiple stress signals to orchestrate Ca2+ signaling and homeostasis.