Key regulator of mitochondrial calcium uniporter (MCU) that senses calcium level via its EF-hand domains (Probable). During development, required in alpha/beta or gamma mushroom body neurons to support olfactory intermediate-term memory in the adult (PubMed:27568554). The topology is subject to debate. RNAi-mediated knockdown results in lethality (PubMed:27568554). RNAi-mediated knockdown in neurons shortens lifespan and severely impairs climbing ability (PubMed:28198506). RNAi-mediated knockdown in the developing eye decreases ommatidia number and disrupts ommatidial array (PubMed:28198506). RNAi-mediated knockdown in neurons and, more specifically, in alpha/beta or gamma mushroom body neurons, impairs mitochondrial calcium entry and decreases intermediate-term memory after conditioning (PubMed:27568554). Does not affect olfactory learning (PubMed:27568554). Belongs to the MICU1 family. MICU1 subfamily.