Visual Pigment Like Receptor Peropsin (RRH)

The RPE is a conduit for serum nutrients, phagocytoses 10% of the mass of each photoreceptor outer segment on a diurnal schedule, mediates the isomerization of retinal from all-trans to 11-cis, and contributes to the generation of a standing electrical potential across the eye.

The deduced 337-amino acid RRH protein, which shares 80% amino acid identity with mouse Rrh, has all the structural features of a GPCR. Sequence analysis revealed that RRH is highly similar to numerous vertebrate and invertebrate visual pigments. RRH contains a lys at the position corresponding to lys296 in rhodopsin (RHO), a hallmark of visual pigments, and like many invertebrate visual pigments, RRH has a tyr instead of glu at the position corresponding to glu113 in RHO.