SOC channels

Store-operated channels (SOCs) are ion channels located in the plasma membrane of cells. These channels are most studied in regard to their role in calcium entry into the cytoplasm from extracellular milieu. There are other SOC channels selective to other ions. Calcium SOCs are especially important for the cell because they are the major source of intracellular calcium; and calcium itself is involved in a wide array of vital cellular functions. SOCs are so called because they are activated by intracellular calcium (particularly the endoplasmic reticulum (ER)) stores depletion by both physiological or pharmacological processes.
See also.
Calcium release activated channel
References.
Lewis RS., "The molecular choreography of a store-operated calcium channel", Nature. 2007 Mar 15;446(7133):284-7
Thamara Hewavitharana, Xiaoxiang Deng, Jonathan Soboloff and Donald L. Gill, "Role of STIM and Orai proteins in the store-operated calcium signaling pathway", Cell CalciumVolume 42, Issue 2, August 2007, Pages 173-182.