Updated project metadata. Mitochondria play a key role in Ca2+ homeostasis and thus the regulation of metabolism and cell death. The MCU is an ion channel that mediates the rapid and highly selective uptake of Ca2+ into the mitochondrial matrix. However, an in-depth characterization of the molecular links that couple MCU-dependent Ca2+ entry with mitochondrial function is lacking. We performed 50 pulldowns from MCU complex reporter cell lines and built a protein network of statistically significant interactors