Mapping of evolutionarily coupled residues onto the x-ray structure of the Kv1.2/Kv2.1 paddle chimera. The Cα atoms of all coupled residues are identified with small spheres, and S4 Arg residues are shown as sticks. 19 coupled pairs that are positioned to interact directly are connected with dashed blue lines between S1 and S2 and with dashed magenta lines between S2 and S3. Five coupled pairs whose positions in the structure are not compatible with direct structural interactions are connected with dashed green lines. The 24 coupled pairs are those listed in Table S3 in Palovcak et al. (2014).