Cryo-EM map of SLC9C1 in nanodiscs (coloured as in Fig. 3a) highlighting the only interaction between the cytoplasmic assembly (ICH7, purple) and the transporter module (TM7, light grey) (left). A peripherally located PA lipid next to TM7 is also shown (blue). Top right, magnified view of the maps showing the interactions between Lys939 in ICH7 and TM7. Bottom right, cartoon representation of SLC9C1 with a cryo-EM mesh (grey) depicting the detailed interactions between ICH7 (purple) and TM7 (grey) with labelled residues (stick form). The yellow dashed lines show mostly hydrogen-bond distances of 2.4 to 4.0 between Lys939 and the backbone of TM7 and the side chains Ser340 and Ser342. Further ICH7–TM7 interactions are formed between Asn943 and His292 and a -cation interaction between Phe294 and Arg940.
