Figure 5.

Activation mechanism of the STIM1/Orai signaling machinery. The scheme visualizes STIM1 and Orai1 in the resting state (left) and activated state (right). Upon STIM1 binding, Orai1 C-terminus is proposed to extend ~45 Å into the cytosol (right). The main and indispensable coupling sites for STIM1 represent the Orai1 C-terminus. The hinge plate, loop2, and N-terminus of Orai1 are additionally supposed to interplay with STIM1, either directly or indirectly (as indicated by the double-sided arrows and question marks).