FIGURE 3.

Orai1 localizes to the cell membrane when expressed prior to STIM1-485. A, overexpression of the fragment from STIM1 encompassing residues 485–685 does not rescue the ER disruption phenotype produced by STIM1-485. Oocytes were left untreated (control (Con)) or injected with RNA encoding residues 486–685 of STIM1 (20 ng) and allowed 24 h to express. Both batches were then injected with GFP-Orai1 (2 ng) and Ch-STIM1-485 (10 ng) and allowed an additional 48 h to express. Scale bar = 5 μm. B, oocytes were injected with GFP-Orai1 (2 ng) and allowed 24 h to express before injecting Ch-STIM1-485 (10 ng) and incubated for an additional 48 h. The orthogonal section and two different focal planes as indicated by the bars on the left of the orthogonal section are shown. Under those conditions, although some Orai1 was retained intracellularly, it was enriched at the cell membrane.