Orai 's cell physiology a protein , which in the plasma membrane ion channels with a high selectivity for calcium - ion forms.
So far, three subtypes of Orai have been identified: Orai1, 2, and 3.
When the calcium concentration in the
endoplasmic reticulum (ER) drops, Orai channels are activated by the calcium sensor Stromal interaction molecule (STIM, especially STIM1) in the membrane of the ER. The intracellular calcium stores are replenished by the influx of calcium ions from the extracellular space into the cytosol through Orai channels. Orai proteins thus fulfill an important function for calcium homeostasis in the cell.
↑ Andriy V. Yeromin, Shenyuan L. Zhang, Weihua Jiang, Ying Yu, Olga Safrina & Michael D. Cahalan:
Molecular identification of the CRAC channel by altered ion selectivity in a mutant of Orai. Nature 443 (September 14, 2006), pp. 226-229 doi : 10.1038 / nature05108 <img src="https://de.wikipedia.org//de.wikipedia.org/wiki/Special:CentralAutoLogin/start?type=1x1" alt="" title="" width="1" height="1" style="border: none; position: absolute;">