Figure 1.

Amino acid sequences of human and mouse peropsin aligned with human rhodopsin, octopus rhodopsin, bovine RGR opsin, and squid retinochrome. The positions of the retinylidene Schiff base (Lys-296 in rhodopsin) and its counterion (Glu-113 in rhodopsin) are indicated by arrowheads. The region encompassing the seventh putative transmembrane segment of squid retinochrome has been manually aligned to bring Lys-275, the site of the retinylidene Schiff base (26), into register with Lys-296 in human rhodopsin. h, human; m, mouse; o, octopus; b, bovine; s, squid.