Stromal interaction molecule 1 (STIM1) is a transmembrane protein that is essential for store-operated Ca(2+) entry, a process of extracellular Ca(2+) influx in response to the depletion of Ca(2+) stores in the endoplasmic reticulum (ER). STIM1 localizes predominantly to the ER, upon Ca(2+) release from the ER, STIM1 translocates to the ER-plasma membrane junctions and activates Ca(2+) channels. Recombinant Calmodulin tagged STIM was expressed in E.coli and purified by using conventional chromatography techniques. Synonyms: GOK, D11S4896E, Stromal interaction molecule 1, STIM1, Stromal interaction molecule 1 D11S4896E, SIM, STIM 1, Stim1 stromal interaction molecule 1. NCBI no.: NP_003147