1.A.77.1.17
CMU of 248 aas and 2 TMSs.  It functions together with the EMRE regulatory protein (TC#8.A.45.1.6). MCU and EMRE form the minimal functional unit of the mitochondrial calcium uniporter complex in metazoans. Wang et al. 2020 functionally reconstituted an MCU-EMRE complex from the red flour beetle, Tribolium castaneum, and determined a cryo-EM structure of the complex at 3.5 Å resolution. They demonstrated Ca²⁺ uptake into proteoliposomes containing the purified complex. Uptake depended on EMRE as well as cardiolipin. The structure revealed a tetrameric channel with a single ion pore. EMRE was located at the periphery of the transmembrane domain and associates primarily with the first TMS of MCU. Coiled-coil and juxtamembrane domains within the matrix portion of the complex adopt markedly different conformations than in a structure of a human MCU-EMRE complex, suggesting that the structures represent different conformations of these functionally similar metazoan channels (Wang et al. 2020).