MCUR1 is a critical regulator of the mitochondrial calcium uniporter (MCU) complex that controls calcium entry into mitochondria 1. It functions as a scaffold protein facilitating assembly of MCU complex membrane components 2 and directly interacts with MCU to enable uniporter-mediated calcium uptake 1. Beyond calcium regulation, MCUR1 homologs regulate mitochondrial proline metabolism, suggesting evolutionary conservation of metabolic functions 3. Mitochondrial calcium homeostasis mediated by MCUR1 is essential for cellular bioenergetics, respiration, and survival pathways 2. During aging, MCUR1 expression declines in skeletal muscle, impairing mitochondrial calcium uptake and contributing to sarcopenia and muscle dysfunction 4. MCUR1 dysfunction impairs erythropoiesis under hypoxia through reduced mitochondrial calcium uptake and altered cytosolic calcium signaling via the CAMKK2-AMPK-mTOR axis 5. Clinically, MCUR1 dysregulation contributes to multiple disease pathologies. Altered mitochondrial calcium dynamics due to MCU dysfunction promote cardiomyocyte apoptosis in myocardial ischemia-reperfusion injury; increasing MCUR1 expression protects against this damage 6. MCUR1 is genetically associated with type 2 diabetes risk in the context of periodontitis 7. Disrupted mitochondrial calcium cycling generally contributes to heart failure, stroke, neurodegeneration, and cancer 2.