Figure 1.

Elevations of intraneuronal [Ca²⁺] are the result of an influx across the plasma membrane and the release from the ER through various channels and receptors. The low intraneuronal Ca²⁺ level is then maintained by the activity of Ca²⁺-binding proteins (CaBP) and involves the sodium-Ca²⁺ exchanger (Na⁺/Ca²⁺) acting in concert with the ATP-dependent Ca²⁺ pumps located at the plasma membrane and the ER. Depletion of ER Ca²⁺ content activates the store-operated Ca²⁺ entry (SOCE) pathway.