Sustained and balanced Ca2+ increase upon T-cell receptor activation is crucial for regulation of essential T-cell functions including clonal expansion, differentiation and cytokine secretion. Thereby, mitochondria play an important role and take up Ca2+ to support elevated bioenergetic demands. The protein machinery that regulates Ca2+ flux across the inner mitochondrial membrane; the mitochondrial calcium uniporter (MCU) complex, could be thus implicated in T-cell immunity. However, the exact role of mitochondrial Ca2+, and hence, MCU in T-cells is not fully understood. Here, we provide proteomic data of downregulation of MCUa in rat CD4+ T-cells along with control T-cells.