The Evolutionary Relationship between Microbial Rhodopsins and Metazoan Rhodopsins

Figure 1

Structure alignment of squid rhodopsin (2Z73:A|PDB, metazoan rhodopsin), bovine rhodopsin (1U19:A|PDB, metazoan rhodopsin), Anabaena sensory rhodopsin (1XIO:A|PDB, microbial rhodopsin), Natronomonas sensory rhodopsin II (1GU8:A|PDB, microbial rhodopsin), Halobacterium salinarum bacteriorhodopsin (1JV6:A|PDB, microbial rhodopsin), Natronomonas halorhodopsin (3A7 K:A|PDB, microbial rhodopsin), and Salinibacter ruber xanthorhodopsin (3DDL:A|PDB, microbial rhodopsin). Squid rhodopsin is used as the template for delineating seven-transmembrane helices. Shaded residues are structural homologues. Conserved tryptophan and tyrosine in WXXY motif are marked with black asterisks. The retinal-binding lysine is in bold style and boxed. The aspartic acid in microbial rhodopsin corresponding to the retinal-binding lysine in metazoan rhodopsin is in bold style and underlined. The test region is marked with thin lines.