Location of charged residues in the S1–S4 segments of Slo2.1 channel subunits. (A) Sequence alignment of S4 segments for Slo and Kv1.2 channels. Numbering on top refers to residues in hSlo2.1, and box indicates the boundaries of the S4 segment. Basic residues are colored red, and acidic residues are colored blue. (B) Diagram of a single Slo2.1 subunit showing location of charged amino acids in the S1–S4 segments.