Fig. 2

Interkingdom alignment and in silico modeling of ClC family antiporters. a Amino acid alignments for external (left) and internal (right) gating domains in genes annotated with COG0038 (H⁺/Cl⁻ antiporter ClcA) in L. reuteri, E. coli, mouse, and human (see Additional file 3: Table S3 for gene/genome identifiers). Antiporters and channels are grouped separately and sequence logos (top) denote the conservation of each residue in the antiporter class. Gating glutamate residues are marked (★). Residues are colored by side chain chemistry (aromatic—black, acidic—red, basic—blue, nonpolar—yellow, polar—green). b The ribbon model of ClcA is shown in red, overlapped with models for EriC (white) and EriC2 (blue). Gating glutamate residues are displayed as space-filling atomic surfaces. The external gate is displayed in green (ClcA E148, EriC E144, EriC2 E139), and the internal gate is highlighted in yellow (ClcA E203, EriC E199, EriC2 E193). Models were generated with SwissModel, and visualized with MOLMOL