This entry represents a group of calcium uptake proteins, including MICU1/2/3 from humans. They contain the conserved EF-hand Ca2+-binding domains. MICU1 and MICU2 are the main regulators of the mitochondrial Ca(2+)-uniporter (MCU) []. MICU2 forms a heterodimer with MICU1 to modulate MCU channel activity []. MICU3 a tissue-specific enhancer of mitochondrial calcium uptake [].