P2X1 and P2X4 receptors are expressed with Orai1 and STIM1 at the immune synapse. Confocal live-cell images of Jurkat cells coexpressing EGFP-tagged P2X1 or P2X4 receptors and either Orai1-EYFP (A,C) or STIM1-ECFP (B,D). Unstimulated cells show uniform Orai1, STIM1, and P2X1 and P2X4 receptor distributions (top panels) that localize at the immune synapse within 30 minutes of stimulation with anti-CD3/28 antibody-loaded beads (marked with asterisks in bottom panels). Scale bars represent 10 μm.