Aligned with ClustalO, amino acid residue types colored according to Clustal scheme in Jalview, * indicates DBD footprint residues, # LBD footprint residues. Black box shows the DBD, red box represents the LBD. Sequences from top to bottom (organism, identifier): Trichoplax adhaerens, TaRXR ID 53515; Homo sapiens, sp|P19793|RXRA_HUMAN; Homo sapiens, sp|P28702|RXRB_HUMAN; Homo sapiens, sp|P48443|RXRG_HUMAN; Xenopus laevis, RXR alpha, sp|P51128|RXRA_XENLA; Aurelia aurita, RXR, tr|S5ZWR0|S5ZWR0_AURAU Retinoid X receptor; Tripedalia cystophora, RXR, tr|O96562|O96562_TRICY Retinoic acid X receptor; Drosophila melanogaster, USP, sp|P20153|USP_DROME. DNA binding domain (DBD, red line), Ligand binding domain (LBD, green line), dimerization domain (yellow line) and amino acid residues critical for 9-cis-RA binding (conserved—red rectangles, not conserved—pink rectangles) are indicated. Readers with specific color preferences may download the compared sequences (File S1) and create the Clustal scheme with different color specifications using the Jalview program (http://www.jalview.org/).