MCU (mitochondrial Ca²⁺ uniporter) makes the calcium go round

Store-operated Ca²⁺ entry (SOCE) is a major mechanism controlling Ca²⁺ signaling and Ca²⁺-dependent functions and has been implicated in immunity, cancer, and organ development. SOCE-dependent cytosolic Ca²⁺ signals are affected by mitochondrial Ca²⁺ transport through several competing mechanisms. However, how these mechanisms interact in shaping Ca²⁺ dynamics and regulating Ca²⁺-dependent functions remains unclear. In a recent issue, Yoast et al. shed light on these questions by defining multiple roles of the mitochondrial Ca²⁺ uniporter in regulating SOCE, Ca²⁺ dynamics, transcription, and lymphocyte activation.