Amino acid sequence alignments of ACR proteins and ACT domains. (A) Sequence alignment of Arabidopsis ACR11 and ACR12 proteins. ACT domains are indicated with solid lines above the sequences. Arrowheads indicate the predicted cleavage sites of chloroplast transit peptides. Asterisks shown below the sequences denote the putative ligand-binding sites. (B) Sequence alignment of ACT consensus sequence (ACTc) from Pfam01842, and ACT domains from ACR11 (ACR11.1 and ACR11.2), ACR12 (ACR12.1 and ACR12.2) and GlnD (GlnD1 and GlnD2). The predicted secondary structure of the ACTc is shown above the sequences. Arrow indicates the conserved glycine residue in the β1-α1 loop region. Identical and similar amino acid residues are shaded in black and gray, respectively.