STIM1

Stromal interaction molecule 1 is a is_associated_with::protein that in humans is encoded by the STIM1 is_associated_with::gene. STIM1 has a single is_associated_with::transmembrane domain, and is localized to the is_associated_with::endoplasmic reticulum, and to a lesser extent to the is_associated_with::plasma membrane.

Even though the protein has been identified earlier, its function was unknown until recently. In 2005, it was discovered that STIM1 functions as a calcium sensor in the is_associated_with::endoplasmic reticulum. Upon activation of the is_associated_with::IP3 receptor, the calcium concentration in the endoplasmic reticulum decreases, which is sensed by STIM1, via its is_associated_with::EF hand domain. STIM1 activates the "store-operated" is_associated_with::ORAI1 calcium is_associated_with::ion channels in the plasma membrane, via intracellular STIM1 movement, clustering under plasma membrane and protein protein interaction with ORAI isoforms. is_associated_with::2-Aminoethoxydiphenyl borate (2-APB) and 4-chloro-3-ethylphenol (4-CEP) cause STIM1 clustering in a cell and prevent STIM1 moving toward plasma membrane.

Interactions
STIM1 has been shown to interact with is_associated_with::STIM2.