SOAR is the Orai1-activating region of STIM1, where STIM1 are calcium sensors in the endoplasmic reticulum. As the store of calcium is depleted the calcium sensor in the ER activates Orai1, a Ca2+-release-activated Ca2+ (CRAC) channel, in the plasma membrane. The SOAR region, which runs from residues 340-443 on UniProtKB:Q13586, forms a dimer, and is essential for oligomerisation of the whole of STIM1 [1].

1: Structural and mechanistic insights into the activation of Stromal interaction molecule 1 (STIM1). Yang X, Jin H, Cai X, Li S, Shen Y; Proc Natl Acad Sci U S A. 2012;109:5657-5662. PMID:22451904