(A) One dimer of SWELL1 subunits. Charged residues both of opposite and similar charges face each other in the interface between the two LRR domains (insets, top middle and bottom left; blue spheres are positively charged residues (Arg, Lys, and His), red spheres are negatively charged residues (Asp and Glu)). (B) C-termini of the two protomers in a dimer interact with regions of the neighboring LRR domain. Two of three ‘outer’ subunits are removed for clarity. ‘Inner’ subunits may be able to coordinate with one another via a triad of charged residues (E800) at their C-termini (inset, dashed border, top right), while the C-termini of the ‘outer subunit’ may interact with the edge of the neighboring outer subunit via charged residues R688 on LRR12 and/or K732 on LRR13 (inset, dashed blue border, bottom right).