Calcium influx through store-operated Ca2+ entry (SOCE), mediated by STIM-operated Orai channels, is crucial for many cellular functions. To dissect the molecular mechanisms underlying the process of STIM-Orai activation and identify regulators that modify this process, ratiometric imaging of SOCE responses in HEK cells overexpressing STIM and Orai is a routinely used method. Here we describe one commonly used procedure of monitoring SOCE activity with a ratiometric membrane-permeable dye fura-2-AM. Other ratiometric indicators suitable for SOCE measurements are also discussed.
Keywords: Calcium release-activated calcium (CRAC) channel; Fura-2; Fura-4F; Fura-6F; Fura-red; GEM-GECO1; Indo-1; Ratiometric Ca2+ measurements; Store-operated Ca2+ entry (SOCE).