Schematic showing role of STIM1–EB1 interaction in STIM1 translocation to ER–PM junctions during ER Ca²⁺ depletion. The ER is a dynamic organelle that continuously rearranges its structure through the MT to maintain its network and contacts with other organelles including the PM. The binding of STIM1 to EB1 enables ER movement along MT. In the resting state (left), the ER is replete with Ca²⁺, and STIM1 is distributed throughout the ER. EB1 dynamically binds a few STIM1 molecules and traps them from translocating to the ER–PM junction. After ER Ca²⁺ depletion (right), free STIM1 without EB1 restriction is readily translocated to ER–PM junctions once Ca²⁺ is dissociated from its EF hand localized in the ER lumen. EB1 still binds some STIM1 to prevent enhanced SOCE from inducing overload of cytosolic and ER Ca²⁺. This restrictive mechanism is critical for migrating cells in which EB1 restricts STIM1 translocation to activate SOCE at the leading edge of the cells. Enhanced SOCE induces elevation of cytosolic and ER Ca²⁺, which leads to termination of cell migration.