This domain, also known as SOAR, is the Orai1-activating region of STIM1 (stromal interaction molecule 1). STIM1 is a Ca2+ sensor 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 forms a dimer, and is essential for oligomerisation of the whole of STIM1 [].
This entry includes STIMATE from animals and uncharacterised vacuolar membrane protein YPL162C from budding yeasts. STIMATE is a ER-resident multi-transmembrane protein that serves as a positive regulator of Ca(2+) influx in vertebrates. It interacts with ER-resident Ca2+ sensor protein STIM1 to promote STIM1 conformational switch [].
STIM proteins contain a single SAM (sterile alpha-motif) domain and an unpaired EF hand within the highly conserved extracellular region, and the coiled-coil domains thatare conserved in structure and position within the cytoplasmic region []. The EF-hand and SAM domain of the STIM proteins serves as a Ca2+ sensory region []. "Hidden"EF hand and SAM domains have a stable intramolecular association. Destabilization of the EF-SAM association during Ca2+ depletion leads to partial unfolding and aggregation (homooligomerization) []. STIM oligomerization is a key induction step in the activation of Ca(2+)-permeable channels on the plasma membrane. In human cells, STIM1 and STIM2 are regulators of store-operated calcium (Ca(2+)) entry as well as basal cytoplasmic Ca(2+) levels [].
STIM proteins contain a single SAM (sterile alpha-motif) domain and an unpaired EF hand within the highly conserved extracellular region, and the coiled-coil domains that are conserved in structure and position within the cytoplasmic region []. The EF-hand and SAM domain of the STIM proteins serves as a Ca2+ sensory region []. "Hidden"EF hand and SAM domains have a stable intramolecular association. Destabilization of the EF-SAM association during Ca2+ depletion leads to partial unfolding and aggregation (homooligomerization) []. STIM oligomerization is a key induction step in the activation of Ca(2+)-permeable channels on the plasma membrane. In human cells, STIM1 and STIM2 are regulators of store-operated calcium (Ca(2+)) entry as well as basal cytoplasmic Ca(2+) levels [].This entry represents the SAM domain of STIM2.
