Stromal interaction molecule 1 (STIM1) monitors ER-luminal Ca2+ levels to maintain cellular Ca2+ balance. Here the authors find that the STIM1 luminal domain monomer has multiple Ca2+ - binding sites which set the threshold for physiological activation of STIM1 in cells.
- Aparna Gudlur
- Ana Eliza Zeraik
- Patrick G. Hogan
