Diversity and functional properties of bistable photopigments

Abstract

Rhodopsin and rhodopsin-like photopigments function in visual and non-visual photoreceptor cells of various animals. Since the 1950s, photopigments having bistable nature have been found in invertebrate visual photoreceptor cells. The bistable photopigments are characterized by high thermal stability of the active photoproduct as well as photo-interconvertibility between inactive (dark) and active (light) forms. Recent studies have revealed that bistable photopigments are present in the non-visual photoreceptor cells of vertebrates including mammals. This observation means that an understanding of the molecular properties of bistable pigments is critical to the understanding of photoreception not only in invertebrates but also in vertebrates. In this chapter, the molecular characteristics, diversity and structure-function relationships of bistable photopigments are summarized. Recent research progress and future directions of bistable pigment study are also overviewed and discussed.