Figure 1.

Sequence alignment of ClC-Ka, ClC-Kb, rClC-K1, ClC-0, and EcClC. Residues shown to be important for the Ca²⁺ response previously (black stars; Gradogna et al., 2010) or in the present study (red stars) are highlighted, as are those that are implicated by the models but that do not show any impact on the Ca²⁺ response (open stars). The histidine residue responsible for the proton activation of ClC-Ka is marked with a circle. The line indicates the fragment of ClC-0 replaced by the corresponding ClC-Ka sequence in the ClC-0/ClC-Ka chimera. The C-terminal 150 residues of the ClC-K channels are omitted for clarity, as are the terminal residues of ClC-0. Polar (N and Q; green), basic (K, H, and R; lavender), and acidic (E and D; red) residues are also highlighted. The α-helical segments of EcClC are indicated with yellow bars (helices A–R). This alignment is a revised version of a previously proposed alignment (Gradogna et al., 2010; see Materials and methods).