Tags: Protein.
Calcium Release-Activated Channels (CRAC) are specialized plasma membrane Ca2+ ion channels. When calcium ions (Ca2+) are depleted from the endoplasmic reticulum (a major store of Ca2+) of mammalian cells the CRAC channel is activated to slowly replenish the level of calcium in the endoplasmic reticulum. The plasma membrane protein Orai (ORAI1 and ORAI2 in humans) forms the pore of CRAC channel.