Peropsin is a visual pigment-like protein identified following large-scale sequencing of cDNAs derived from human ocular tissues. Peropsin mRNA is found in the retinal pigment epithelium (RPE) of the eye. Peropsin immunoreactivity, localizes the protein to the apical face of the RPE, and most prominently to the microvilli that surround the photoreceptor outer segments. It is thought that Peropsin may play a role in RPE physiology either in light detection as well as monitoring the concentration of retinoids (or other photoreceptor-derived compounds). It may play a role in retinal pigement epithelium physiology either by detecting light directly or by monitoring the concentration of retinoids or other photoreceptor-derived compounds.