A Novel Modulator of STIM2-Dependent Store-Operated Ca2+ Channel Activity

Store-opeated Ca2+ entry is one of the main pathways of calcium influx into non-excitable cells,which entails the initiation of many intracellular processes. The endoplasmic reticulum Ca2+ sensors STIM1 and STIM2 are the key components of store-operated Ca2+ entry in mammalian cells. Under physiological conditions, STIM proteins are responsible for store-operated Ca2+ entry activation. The STIM1 and STIM2 proteins differ in their potency for activating different store-operated channels. At the moment, there are no selective modulators of the STIM protein activity. We screened a library of small molecules and found the 4-MPTC compound, which selectively inhibited STIM2-dependent store-operated Ca2+ entry (IC50 = 1 mu M) and had almost no effect on the STIM1-dependent activation of store-operated channels.