(A) The amino acid sequences of transmembrane regions of T. castaneum, C. europaea, D. discoideum, C. elegans, D. rerio (Zebrafish) and human MCUs are aligned and colored according to the ClustalW convention (NCBI Reference Sequence: XP_008192975.1 (T. castaneum), UniProt accession numbers: W2SDE2, Q54LT0, Q21121, Q08BI9 and Q8NE86, respectively). Secondary structures are indicated with cylinders representing α-helices, and residues facing the intermembrane space are indicated with a red line. Residues involved in MICU1-binding are highlighted with red triangles. (B) The amino acid sequences of T. castaneum, C. elegans, D. rerio (Zebrafish) and human EMREs are aligned and colored in the same manner (UniProt accession numbers: D6X268_TRICA, Q9U3I4, A0A0J9YJ98 and Q9H4I9, respectively). Secondary structures are indicated with bars representing α-helices, solid lines representing structured loop regions, and dashed lines representing disordered regions. The acidic C-terminal tails of EMRE proteins are highlighted with a red line. Leu 92 is noted with a red triangle.