Sequence analysis of the three transporters. Sequence alignment between MtrF and VcINDY (A), YdaH and VcINDY (B), and MtrF and YdaH (C), extracted from the structure alignment obtained with the Fr-TM-align program. The sequence identity and similarity are given in each case. The alignment is colored according to the chemical properties of the residues: pale yellow, aliphatic (Ala, Ile, Leu, Met, and Val) and cysteine; cyan, polar uncharged (Asn, Gln, Ser, and Thr); yellow-orange, aromatic (Phe, Trp, and Tyr); red, acidic (Asp and Glu); purple, basic (Lys, Arg, and His); pink, Gly and Pro. The secondary structure (helix) assignments were obtained with DSSP and are indicated by blue rectangles. Black rectangles mark the motifs involved in the substrate-binding sites.