Fig. 4: ORAI isoforms form heteromeric channels.

a–c Representative currents were recorded with a pipette solution containing 10 mM EGTA and elicited by hyperpolarizing voltage steps (holding potential +30 mV) from ORAI-TKO cells co-expressing YFP-STIM1 (4 µg plasmid) with individual CFP-ORAI isoforms (1 µg plasmid). d, e Peak current densities at −100 mV are shown in d and the extent of ORAI isoform CDI represented as current remaining at 146 ms are shown in e; each data point represents mean ± SEM. f, g Representative currents were recorded with a pipette solution containing 10 mM EGTA and elicited by hyperpolarizing voltage steps (holding potential +30 mV) from ORAI-TKO cells co-expressing YFP-STIM1 (4 µg plasmid) with two CFP-ORAI isoforms (0.5 µg plasmid each). i, j Peak current densities at −100 mV are shown in i and the extent of CDI of ORAI isoform combinations are represented as current remaining at 146 ms and shown in j; each data point represents mean ± SEM. k–m Representative currents were recorded with a pipette solution containing 10 mM EGTA and elicited by hyperpolarizing voltage steps (holding potential +30 mV) from ORAI-TKO cells co-expressing YFP-STIM1 (4 µg plasmid) with 1 µg plasmid of concatenated ORAI isoform heterodimers C-terminally tagged with tdTomato (e.g., ORAI1,2 Tandem). n, o Peak current densities at −100 mV are shown in n and the extent of CDI of ORAI concatemers are represented as current remaining at 146 ms and shown in o; each data point represents mean ± SEM. All data were statistically analyzed using one-way ANOVA with multiple comparisons (*p < 0.05; **p < 0.01; ***p < 0.001; ****p < 0.0001). Comparisons deemed significant are indicated by horizontal bars. Boxplots show the mean, median, and the 75th to 25th percentiles.