Constructs and reagents TMEM203; D1ER, NFAT2 (1–402) were synthesized and cloned into desired plasmids by Genscript USA Inc. pTUNE-TMEM203, RFP-fused organelle markers were purchased from OriGene Technologies Inc. Various antibodies were purchased from respective companies as mentioned—STIM1 (Cat # 4916) and SERCA2 (Cat # 4388) from Cell signaling technologies. IP3R antibody (# 610312) from BD Bioscience, INSIG1 (Cat #ab70781) from Abcam and M2 FLAG from Sigma Aldrich. siRNA against Human TMEM203 were from Qiagen—siRNA TMEM203—CAGGCACTGCTTGGCTTACTA (Cat #-SI00633185); control siRNA were purchased from Dharmacon-Thermo Scientific—Non-Targeting siRNA #1(Cat #-D-001210-01-05).